Classé Sigma SSP AV Processor and AMP5 Review

Update 6/27/17:  Classé just released the Sigma SSP MkII Upgrade with Dolby Atmos/DTS:X and 4K UHD Support.

For die-hard audiophiles, Classé needs no introduction.  The company first got its start building amplifiers back in 1980. However, when Classé joined the B&W Group in 2001 it propelled the company to a whole new level in the audio and home theater world.  The B&W group is comprised of Bowers and Wilkins Loudspeakers, Classé, and Rotel.  

Since that time, many an audiophile has auditioned Bowers & Wilkins’ flagship speakers powered by Classé amplification.  I know I have.  Indeed, thanks to the distribution channels, financial resources, and technology of Bowers & Wilkins, it is safe to say that Classé is now perched upon the upper echelon of audio electronics. 

One thing that has particularly struck me about Classé’s electronics is the company’s focus on industrial design. Sleek curves and minimalist style highlighted by a thin-film-transistor (TFT) LCD touch-screen display have all been typical hallmarks of Classé’s products for years. It's some of the best looking gear in audio.  However, no matter how sleek and clean the products have looked, Classé’s lineup has had a very large physical footprint.  Complementing that large footprint has been an equally hefty price point.  

The smooth, sleek curves of the Classé 5300 Five Channel Amplifier

All that changed this past September when Classé announced their Sigma series, consisting of the 7.1 channel Sigma SSP preamp-processor (MSRP $5,000), the Sigma AMP2 amplifier (MSRP $3,500, rated at 2 x 200W into 8 ohms) and the Sigma AMP5 five-channel amplifier (MSRP $5,000, rated at 5 x 200W into 8 ohms).  While still expensive, new Sigma series electronics are the most affordable Classé products to date.  

I asked Dave Nauber, Classé’s president, about the goals of the Sigma series.  "We believe that customers who want something better than mainstream products are looking for a combination of higher performance, quality and exclusivity," Dave told me.  "And by exclusivity I mean that they prefer something that is special—not everyone knows about it and you can’t find it everywhere."

"First and foremost,” Dave went on to say,  “We build products for music lovers and the Sigma series is designed for music lovers or audiophiles who happen to have a TV between their speakers or want to have a theater in a family room where the number and location of speakers is limited, even if the budget is not.”  For Dave and the Classé team, the Sigma series is for individuals who prioritize audio quality.  Dave made it a point to tell me, “The Sigma series is clearly different and better than mass market products priced below it and the entry level components of other high-end brands that are priced just above it.”

Each product in the Sigma series is based on a small, standardized, and minimalist form factor.  While Classé has shrunk the outer box, one look will tell you that these units have all the typical hallmarks and performance on paper that make them all Classé.  Each component has exactly the same low-profile, custom-installer-friendly 2U chassis.  In fact, just looking at the front or side of the units, you’ll be hard-pressed to tell them apart.  

 I talked with Dave about the pedigree and circuitry of the Sigma SSP processor.  “The Sigma SSP shares common circuit blocks and critical parts with our more expensive Delta series CP-800 Stereo Preamp/Processor,” he said. “The digital circuits for USB, Network, Coax and Optical signal paths are literally cut and pasted from the CP-800. We use the same DACs for Left and Right channels as the CP-800, but there is one stereo DAC per channel (differential) rather than two (dual differential), so the circuitry is not as complex or costly. As an analog preamp, the Sigma SSP is extremely quiet and sounds beautiful. It also supports the same optional phono module as the CP-800. For anyone who wants a serious high-end stereo preamp that can integrate with AV sources and even provide multichannel processing, the Sigma SSP is a powerhouse.”

Top view of the Classé Sigma SSP's internal Circuitry

In both audiophile circles and in our own testing at Audioholics, Class D amplifiers have been a mixed bag.  To be frank, most Class D designs haven’t impressed us because of their performance.  However, it’s important to underscore that like so many other manufacturers, Classé is not using someone else’s Class D modules under the hood.  

I took the opportunity to talk with Dave a bit about Classé’s Class D solution.  “Unlike most Class D solutions on the market today, we do not use an off-the-shelf module. The design is a bespoke Classé solution. We expanded the Classé design team to bring decades of experience to the table in this design, employing a true digital topology to harness the power of DSP to achieve our design goals. Using the typical off-the-shelf options would have left us with certain technical/performance limitations such as excessive dead band time [see explanation below] that would have unacceptably limited the performance potential of the amplifiers.”  

Dave went into detail about one of the things that differentiates Classé’s Class D implementation over other vendors.  “There are many specific details, but our ability to achieve what’s called low dead band time (<3ns) is at the heart of why these amplifiers don’t sound like typical class D designs.  There’s quite a lot to talk about, but by reducing dead band time to such a small amount (an order of magnitude or more better than most other solutions), we start with very low distortion and therefore use only a small amount of overall negative feedback. We also supply lots of power to the audio circuitry, which is a shortcoming of many other designs.”  (If you’re interested more on this topic, Classé has a white paper at www.classeaudio.com/documents).  Classé says that the end result of their engineering should be “superb musical sonic performance along with other class D benefits like small size, low heat dissipation and high efficiency.”

 Even though I was familiar with Classé from past experience, I was still excited at the prospect of taking the new Sigma line a spin.  My review setup consisted of the Sigma SSP and Sigma AMP5.  

Classé Sigma SSP and AMP5 First Impressions

Unboxing equipment becomes a tedious rote for reviewers that it is senseless to write about.  So when something as pedestrian as unboxing equipment catches your eye, you know someone’s paid attention to detail. 

Few companies understand how important it is to create a premium experience for their customers.  The box is part of the product experience. Apple is a well-known a master of this craft.  Not only does Apple meticulously design their products, but they also focus intently upon the packaging—from outer design and feel to each step you take to lift the product out of the box.

Unboxing the Classé review units told me that Classé's industrial designers paid attention to some of those same details.  The two boxes housing the Sigma SSP and AMP5 were identical in size.  The outer boxing reflected Classé’s nod to modern style and clean lines.  It was smooth and white with minimalistic detailing.  It eschewed the typical cardboard construction and feel you get with most AV products.  It felt higher quality.  Opening the box revealed a white, similarly branded “Accessories” box.  

Included in the neatly laid out accessories box was as set of brushed aluminum magnetic caps for rack mounting (more on that below) and a Classé-branded black and silver USB stick that contains the user manuals for every Classé product. 

There’s no paper manual included at all, which may not sit well with everyone.  The USB stick also doubles to provide firmware updates for the processor that are done via USB. Underneath, the Sigma SSP Processor and AMP5 were covered in a Classé branded black cloth. 

 

Included accessories of the Sigma SSP and Sigma AMP5 

Think about it for a moment. It would have been far easier to use brown cardboard and labels at any point.  Instead, Classé thought through the small details to convey a sense of the product’s premium lineage or exclusivity.  Attention to such detail quickly carried over to the industrial design of the units themselves.  Classé employed the design firm Goodwin-Hartshorn in the UK to develop the industrial design for the Sigma series.  

The results paid off in spades.  The units are strikingly minimalist.  Clean lines abound.  On the AMP5, the clear, five-way binding posts are beautifully branded with the Classé logo.  To the last detail, the units screamed, “This is all Classé.” 

 

The five way binding posts on the Sigma AMP5 are branded with the Classé logo showing meticulous attention to industrial design and branding throughout

In contrast to every other Classé processor, the volume dial on the Sigma SSP lies flush to the unit’s front face.  You scroll it like an iPod scroll wheel.  You cannot handle it like a traditional volume dial.  HDMI, headphone, and USB inputs grace the front of the panel with the menu and mute buttons recessed flush against the curved black TFT screen’s glass in the middle of the unit.  

The top and sides of both units are smooth and clean without any vent holes whatsoever.  In case you are wondering, the entire chassis handles heat dissipation. The smooth surfaces accentuate the brushed black, aluminum styling and further add to the silky look of the units. 

Top view of the AMP5.  The heat sinks are covered in a pink-colored material that comes into contact with the top cover and helps dissipate any heat to the entire chassis.  In all my testing, the AMP5 never go hot.

I experienced first-hand how these units have been specifically designed to cater to high-end custom installations. Gone are the rounded, hallmark curves of Classé’s CA-series amps or SSP-800 and CP-800 processors.  Instead, you have a more traditional—yet modern-looking—box that caters to nuances for rack-mounting.  

For example, both units share exactly the same footprint and enclosure.  Only the faceplate is different.  Using the same form factor for the processor and the amplifiers in this series makes rack design and installation planning a piece of cake.  Every unit is a 2U design. In fact, if you are going to rack mount the units, there’s no need purchase an additional rack kit or use rack ears that will compromise the styling of the Sigma and AMP5.   The rack mount for the units is integrated into the side panels of every unit.  What a brilliantly simple idea; yet, silly as it sounds, it’s one of the most beautiful things to see in rack mountable gear.  

The Classé Sigma AMP5 with integrated rack ears and magnetic caps

Simply unscrew the sides, flip them around and bingo!  You now have 19” rack compliant ears that seamlessly match the fit and finish of the units.   Remember those magnetic caps I mentioned at the unboxing?  Classé includes those magnetic caps to adhere to the mount ears.  They hide the rack mount screws and make the installation look completely clean.  Now, that is attention to detail. Whether you’re rack mounting or keeping them in a traditional cabinet, the Classé units will be functional and look great in either environment.

When I asked Dave how they came up with that idea, he told me that their industrial design firm, Goodwin-Hartshorn listened to what Classé wanted about the overall design goals for both shelf and rack-mount applications and came up with this brilliant solution. "Everyone who sees it loves it," he told me. 

 A key secret to Classé’s minimalist design lies in their longtime commitment to TFT touch-panel displays.  Everything you need to do on the processor is handled via the integrated touch-screen display.  Coming from a world where mobile devices sport retina displays, I found the TFT display to be startlingly low-resolution.  It was like going back to 480i after being accustomed to 1080p. Nevertheless, the display is infinitely flexible and functional.  You can set the display’s brightness level and time-out to turn it completely off so that it doesn’t sit as a glowing distraction.

You can rename each source, input, and configuration via the display so that it’s customized to your specific installation. The display will show you the current volume in large, clear numbers that you can see across a room.  Under the volume it displays the current input, video signal (including whether it is 2D or 3D), the audio codec being used, the audio signal’s bitrate, and what audio mode you currently have selected.  

The TFT Display can show you a real-time video preview of your source

With a simple menu click, you can even use the TFT display to give you a real-time video preview of your selected input source.  If you are having HDMI problems you can see if the signal is arriving properly to the processor or if you have the Sigma SSP in a different room, you can monitor the input signal right on the unit for simple debugging.  Perhaps best of all, because it’s a software-driven display, Classé can update the menu offerings and features anytime with a simple firmware update.  

I’ve had quite a bit of experience dealing with multichannel processors over the years and I found the Classé to be among the most flexible.  The Sigma SSP just might be the definition of versatility. It combines the flexibility of Swiss Army knife with the precision of a surgeon’s tool in an easy-to-use package.   There’s simply not enough room here to even pretend to detail what you can do with this processor.  It’s just awesome.

What Classé chose to exclude in the design is as important to note as what is included.  Fitting electronics into such a small form factor certainly needed some compromises.  However, some that I observed are due to form and others to Classé’s philosophy. Let me explain.

There’s no video processing or scaling.  Dave told me that Classé doesn't believe that the audio processor is the proper place for video processing so the Sigma SSP offers straight pass-thru of video signals.  Classé is not alone in this belief.

Nevertheless, unlike some other competitors who omit video processing, Classé does give you an on-screen display (OSD).  When an OSD is required, it is overlaid on the video signal using an FPGA (field-programmable gate array) that writes the video from the touchscreen onto the screen, changing only those pixels that represent the OSD and passing through those that are part of the picture being displayed.

The Classé Sigma SSP's OSD is elegant.  It shows you the input source, incoming audio channels and sampling rate, volume, and video signal.   The OSD t takes up quite a bit of screen real estate, especially on older 480p sources. 

In this way, even when an OSD message appears, the rest of the screen remains unaffected. While Classé’s OSD messages are rendered nicely on screen, they are quite large and can also become visually obtrusive.  The great news is that you can defeat the OSD in the display setup menu.

Even though Classé extolls the virtues of balanced connections in the manual, they are limited to the front left and right channels on the processor and channels 1 and 2 on the AMP5. The remaining connections are unbalanced. The decision to omit balanced circuits was largely due to budget and the physical restrictions of the Chassis.  

I was curious about the overall circuit design of the units. When Dave and I got a bit more in-depth about the circuitry of the Sigma series he told me that the XLR connections of the units are fully balanced.  He went on to say, “In general for Classé products, we would never use XLR connectors without accompanying balanced circuitry.  For the SSP, you do accurately describe the differential output of the DACs and we maintain that in the analog path, volume control, etc. as well. For the AMP5, the amplifier circuitry is balanced for all channels through to the speaker terminals so even single-ended inputs are converted to balanced immediately on entering the chassis.”

The Sigma series embraces digital content delivery, but it does so only via Ethernet. There is no WiFi option available.  Wired connections are much more reliable with less latency. 

A potentially major compromise with the Sigma SSP is deciding how to handle your setup.  The sixth and seventh speaker outputs are called AUX 1 and AUX 2.  You can use them in only one of the following configurations: as the rear channels in a 7.1 surround system; as front height channels; as a second parallel audio zone; or as a mirror of the front L and R speakers in a bi-amp arrangement.

The rear view of the Sigma SSP with balanced L and R channels and assignable AUX 1 and AUX 2 outputs.  Additional USB and HDMI input ports are located on the front.

From the OSD, you can assign how the AUX output will function.  You can have the AUX speakers function differently for different configurations.

Possibly the most interesting decision for some enthusiasts will lie with the Sigma’s automated room correction or the absence thereof.  Instead of automated room correction, the Sigma SSP comes with nine bands of manual parametric equalization (PEQ) for each speaker.  You can choose to enable the PEQ on a speaker-by-speaker basis or all speakers together.    

Think of the PEQ as smoothing out bumps or valleys at a specific frequency.  Depending on how your speaker and room interact you may have smaller or larger bumps.  Classé’s PEQ is very flexible to allow you to handle pretty much any situation.  You can adjust the PEQ center band frequency from 20Hz to 20kHz.  In other words, you have no limit within the audible band of human hearing.

The center gain is the amount of center frequency cut or reduction in volume for that frequency.  You can decrease the center gain by up to 20db or increase it by as much as 3db. Remember that increasing the gain puts much more stress on the amplifier and it’s always better to address peaks than valleys.  For this reason, Classé correctly limited the increase to only 3db. 

Finally you can then set the Q value or the filter width from the center band that the filter will affect.  This value, which can be set from 1-10 will adjust the sharpness of the filter.

This manual approach provides more control to the dealer or installer.  I asked Dave about this point specifically.  “We have a global network of distributors who are familiar with the Sigma series and provide dealer training.  For dealers already familiar with Classé, the setup and operation of the SSP is quite familiar. As always, the most important part of the setup is positioning the loudspeakers and dealing with room problems, which is true of all audio system installations so not unique to Classé system installations.”

On the one hand, Dave is completely right.  Speaker placement is paramount and you want to limit the amount of EQ you are applying.  And when you need to apply EQ, you want to have the proper flexibility, limit EQ to the lower frequencies and let your ears decide. 

On the other hand, this choice underscores a presupposition that these units will be expertly installed by your local dealer.  If you chose to forego dealer installation, beware!  If you don’t know how to take proper measurements and understand what the PEQ settings are doing then you should leave the PEQ disabled and focus your energies on placing all the speakers properly in your room. The bottom line here is that Classé’s approach is a completely valid one but may not please everyone. 

The eight HDMI ports (7 rear and 1 front) are HDMI 1.4.  With UHD displays and content hitting the market I was pleasantly surprised to hear that Classé is planning an HDMI 2.0 and HDCP 2.2 hardware upgrade path for Sigma SSP clients.  The HDMI 2.0 upgrade will upgrade all inputs and outputs. Classé specifically designed the board to be modular to accommodate upgrades.  Dave told me that by the time actual UHD content became available they would have access to the full 600 MHz bandwidth parts. Because the parts have been coming slower than expected Classé plans to offer an interim step later this year for people who want or need it to accommodate UHD Blu-Ray players, which will be appearing at about that time. 

What about immersive audio? 
The SSP does not natively support any immersive audio formats. I asked Dave if there would be a firmware or hardware upgrade to support Dolby Atmos, Auro3D or the newly announced DTS:X.  He told me, “Most surround processors and AVRs have limited DSP capabilities and require shuffling of processing resources to accomplish multiple tasks at once. Would you want your TrueHD signal down-sampled whenever the EQ was engaged? That’s a pretty common technique. The DSP required for doing 3D audio properly (everything at full resolution) in a Sigma SSP is a bit more powerful than what is currently on board, so a hardware upgrade to a new dual DSP will be offered, probably later this year. Anyone who owns a Sigma SSP will have the option to upgrade it if they want to do so.”

Considering that the Sigma is only a 7.1 channel system, I asked what configuration users could select if they upgraded.  Dave said, “As you point out, since we have eight channels, the only 3D application for this model is going to be 5.1.2. At the moment, Dolby Atmos is the only 3D format we are planning to support on the new Texas Instruments platform. Whether others can be accommodated is yet to be determined.”

Classé Sigma SSP and AMP5 Setup and Use

Setting up the Sigma SSP and AMP5 combination was simple and straightforward.  However, because of the keen ability to fine tune the Sigma SSP to the nuances of your setup, I strongly recommend that prospective buyers lay out their setup on paper or work with their dealer in advance to have everything mapped out.  

You can easily create different configurations.  Each input is independently assignable.

Via the OSD, you can custom name any input.  All custom names are reflected in the units's TFT display, the OSD, and the iOS app.

Remember, the Sigma SSP is incredibly flexible: all inputs can be custom named; inputs can be assigned on the fly; preferred sound modes can be set on a source by source basis; and settings can be fine-tuned to suit your specific taste.  Should you accidentally mess up your installation, dealers have the ability to archive/backup settings on the unit and then restore them at a later time.

The Classé SSP gives you flexibility on how to handle your crossover on each speaker.  You can even assign different crossovers for each speaker for each configuration.  You have complete flexibility.

Something as simple as switching sources or audio modes showed Classé’s rabid attention to detail.  Unlike just about every other vendor who gives you a blunt, hard cutover, Classé will fade the audio out and back in so that you do not experience any loud pops or other audio problems that I’ve experienced with other receivers or pre-pros costing thousands.  Who needs a butler when you have the Classé Sigma series?  Using the Sigma SSP and AMP5 was like being pampered with white-glove attention to detail at every turn.  

You can set manually set the crossover slope at either 12db or 24db to suite your taste and your environment.

I loved the system’s CAN-bus (Controller Area Network) that allows multiple Classé components to talk to each other.  Connecting the CAN-bus controller with a standard Ethernet cable and the included RJ45-style terminator enabled the processor to give me real time status of the AMP5 and control it fully.  If I had multiple amplifiers or other components, I would have been able to select them from the SSP’s TFT screen and optionally control each one.

Via the Sigma SSP's CAN-bus controller, you can get detailed information on any Sigma-series component in your chain. For example,  I was able to get detailed information about the Sigma SSP and the operating temperature of the AMP5

Whatever you do on the unit is available in real-time on the available iOS app. I found the app to be a sleek, streamlined option for users who want basic remote functionality and will not be using home automation solutions like Crestron on Control4 with their installation.  I was disappointed that I could not natively integrate the Sigma SSP with my Roomie Remote installation to test advanced automation.  For advanced functionality, an RS-232 interface via an RJ45 connection is available on the rear of the unit.  You cannot configure or automate the Sigma SSP from the iOS app.

The Classé iOS app allow you to control all basic functions of the Sigma SSP.

I did run into a small problem upon initial setup.  When I set up the units, the AMP5 emitted an annoying buzzing sound that I could hear clearly from nearly 30 feet away.  It sounded like the buzzing you get with a faulty transformer.  I spoke with Dave about this.  He indicated that I had an early production model of the AMP5.  A very small handful of the early AMP5 units had a minor manufacturing issue that had since been corrected. What I was describing sounded just like that symptom.

To confirm that was the case, Dave made a special trip to meet me one Saturday morning to check out the AMP5 first-hand.  Dave popped open the top of the AMP5 and, sure enough, it was the early manufacturing issue.  Dave was able to address it in mere minutes easily, on-site. Voila, just like that, the buzzing all but disappeared. 

Dave had just arrived from a trip to China the day before, so I want to express my sincere thanks to him for that effort.  This anomaly gave us a chance to spend several hours together.  Like most of us, Dave is a long-time audiophile.  I appreciated Dave’s deep and genuine passion for audio and Classé’s product line.

Minor problem aside, I was able to configure the Sigma SSP quickly and easily on my network.  In fact, all my iOS and Apple MacOS devices saw the Sigma SSP as a native AirPlay speaker.  If I selected the Sigma and played a song, it would automatically power up and start jamming out music.  Like all AirPlay solutions, sans AppleTV, the Sigma will only stream audio.  

I was able to stream sources over AirPlay via the Sigma SSP's network (Ethernet) input.

Streaming audio from an iPhone or iPad via the front USB was simple and sounded really good.  I was also pleasantly surprised to see that I could charge my iPad from the SSP’s USB port!  Many AV units don’t deliver enough power over USB to charge an iPad.  I tip my hat to Classé on paying attention to such details.  

All in all, I found the Sigma to be super-easy to setup and configure to my taste and the plethora of inputs and connectivity solutions worked as expected out of the box.

Classé Sigma SSP and AMP5 Sound Quality Tests

Dave was kind enough to let me review the Sigma SSP and AMP5 over a period of a few months.  I got to know the electronics fairly well.  I did a portion of my listening using the excellent RSL CG4 and CG24 monitors and Speedwoofer 10 subwoofer that I had in for review (forthcoming).  However, given the price point and target clientele, I also paired the Sigma series with same Revel Ultima2 Salon2 setup as in my Red Dragon monblock amplifier review.  Regardless of which speaker system I paired the Classé units with, the Sigma SSP and AMP5 were exceptional performers on all counts.

From the first listen, I felt as though there was something instantaneously remarkable about these Classé electronics.  The soundstage just opened up. The amplifier was noticeably free of the analytical sound I’ve previously experienced with Class D amps.  In fact, it struck me that the AMP5 was the first Class D-based amplifier that made me forget I was listening to a Class D amplifier—it sounded like a Class AB amplifier.  No matter what I played, the sound was always clean, smooth, and sounded great from top to bottom.

Music

During one particular listening session, I chose to listen to some Ray Charles.  Ray Charles’ Genius Loves Company is a compilation of songs from different musical genres between Ray Charles and some of the notable names in music.  The album, which cleaned up at the 47th Grammy Awards, was released posthumously after Ray’s death in 2004.  

The album opens with a magnificent duet with Norah Jones on Ray Charles’ signature song, “Here We Go Again.”  As the song opened, I just exclaimed, “Oh wow!”   The entrance of Norah Jones's voice was mesmerizing.  Her breathy and intimate yet lush and smooth-textured vocals came through in all their glory.  The hairs on my arms stood on end.  Ray Charles’ voice was likewise spot on. The paradoxical raspiness and clear tonality of his voice rung out beautifully. The organ notes, snare drum, and kick drum were clean, crisp, and precise with resounding control.  

On the rendition of “Sweet Potato Pie,” James Taylor’s voice had a life-like quality to it—clean, pure, and well-defined—while also exhibiting some of the cues that you often get in a “you are there” performance. 

The duet between Ray Charles and Elton John on the track “Sorry Seems to be the Hardest Word” emotionally drew me in.  The smooth warmth of Elton John’s signature vocals through the Classé combo made that easy.  Instruments were placed within a solid soundstage with superb definition.  

“Fever” with Natalie Cole rocked.  The song opens with a deep, beautiful bass line.  Once again, I blurted out, “Wow!” as that bass note kicked in.  Finger snaps, no pun intended, just “snapped.”  Natalie Cole’s voice came through with excellent dynamics.  The song exuded a superb energy. The Classé combination transported me into an instant, club-like atmosphere. 

When “It Was a Very Good Year” came on I got completely lost in the music. I just became pensive on the lyrics—from the solo guitar to the orchestral complement, I became so engrossed that I stopped taking further notes, sat back and just listened. 

The vignettes on those songs carried through on countless artists and genres.  Classical music was especially engaging.  The deeper soundstage and superb dynamics were an exceptional complement to any classical work.  I played several symphonies from Brahms, Verdi’s Requiem, and the exquisite album from the movie Amadeus by the Academy of St. Martin in the Fields.

Female vocals were beautiful.  I went through my usual mainstays such as Adele, Dido, Norah Jones, and Sarah McLachlan among others.  But it was Kasia Lins and Holly Cole who rocked the foundations.  Kasia is a soul and jazz singer/songwriter from Poznan, Poland.  Her jazz cut, “Go Away” from her album, Take My Tears was a siren-song through the Classé and Revel combo.  The body and texture of Kasia’s vocals, the immediacy of the instruments, were all irresistible.  Likewise, the bass lines on Holly Cole’s rendition of “I Can See Clearly Now” were wonderfully rendered in full body and Holly’s beautiful voice had a clean, articulate, and inviting presentation.

If you doubt that a multichannel processor can nail two-channel audio then you haven’t heard the Sigma SSP and Sigma AMP combo.  It was always engaging and deeply satisfying.  

Movies

Movies and multichannel content carried over the Sigma’s two-channel pedigree—they all sounded great.  I didn’t experience a single issue passing 2D or 3D signals through the Sigma SSP.  HDMI switching was uneventful. 

The Theory of Everything chronicles the life and relationship of world-renowned physicist Stephen Hawking and his wife Jane.  The movie, which is based on Jane Wilde Hawking’s book, Traveling to Infinity: My Life with Stephen, hangs on your ability to decipher dialogue.  Any muddiness in the electronics and you’ll have a tough time making out parts of certain scenes.  The Sigma SSP and AMP5 combo easily delivered the goods where other AV receivers or processors would have had you cranking up the volume simply to make out the dialogue.  At one point in the movie, fireworks spray the screen.  I was taken aback by the stark sensation of openness.  Not only did the fireworks have a realistic pop to them but their delicate decay in a deep, three-dimensional space was uncanny.

 

Tron Legacy is an easy go-to disc when you want to give your system a workout or floor your friends with an intense top to bottom audio experience.  The Sigma electronics mastered the show rendering a flawless, enveloping, three-dimensional sound field.  Again and again, I was taken aback by the increased sense of space and depth that the Sigma combo rendered on just about everything I threw at it.  The audio assault from the Recognizer that comes to pickup Sam Flynn was intense.  At all times, the Sigma SSP clamped its grips on the audio track and not once did I feel like the AMP5 was running out of steam.  You want raw, no-holds-barred, authoritative multichannel audio? Look no further than the AMP5. It delivers the goods. 

Oh wait! I completely forgot, this is a Class D amp, right?  Even with a full-on pounding, the AMP5 only got very warm to the touch.  I do not think I could pay Classé a bigger complement than to say that the amp didn’t call attention to itself sonically at any point.  It simply got out of the way.   

I threw everything at the Sigma Series: TV, Netflix, and movie trailers, including the new Avengers: Age of Ultron, Star Wars: The Force Awakens, and Batman v. Superman trailers at house-throttling levels.  No matter what I played, the Sigma SSP and AMP5 didn’t flinch.  

Classé Sigma SSP and AMP5 Conclusion

The Classé Sigma SSP and AMP5 combination is a one-two knockout punch that will thoroughly satisfy the stingy audiophile and most demanding home theater enthusiast.  Whether you’re talking about traditional analog and digital sources or network streaming, the Sigma SSP is built to deliver the ultimate sonic spectacle.  The meticulous focus on industrial design on this series is stunning.  Such focus will give any prospective buyer real pride of ownership to show off these pieces. 

Yes, there are potentially strategic feature tradeoffs with the Sigma SSP and AMP 5 such as limited balanced connections, manual PEQ, and how to handle the AUX 1 and AUX 2 outputs. However what the Sigma series delivers sonically--plus an upgrade path to HDMI 2.0, HDCP 2.2, and immersive audio--is nothing short of beautiful and glorious. 

At $10,000 MSRP for a 5.1 configuration and $13,500 for a 7.1 configuration with the  AMP2 the Sigma series is not for the faint of heart and wallet.  Rather, the Sigma series is for the discerning buyer who has the funds to mate these electronics with equally stellar-performing speakers. Such a marriage will ensure sonic bliss for years to come. For my part, I know I’ll be very sorry to see this combo head back to Classé.  Highly recommended.

Update 6/27/17:  Classé just released the Sigma SSP MkII Upgrade with Dolby Atmos/DTS:X and 4K UHD Support.

The Score Card

The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:

Performance × Price Factor/Value = Rating

Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.

Audioholics Rating Scale

• — Excellent
• — Very Good
• — Good
• — Fair
• — Poor

Metric	Rating
Multi-channel Audio Performance
Two-channel Audio Performance
Network Features
Bass Management
Build Quality
Fit and Finish
Ergonomics & Usability
Ease of Setup
Features
Performance
Value