AV Tip: Power Off Equipment When Making Connections
While most modern A/V receivers and amplifiers have built in short circuit and fault protection, its always a good idea to play it safe when connecting equipment. I've personally blown a couple of expensive amplifiers with poorly designed short circuit protection hot swapping cables during listening or bench tests. Thus the recommendations below are worth heeding.
When making connections to receivers and amplifiers (especially when working with speaker wires), make sure that the equipment is turned off first. It's not required, but it's a lot safer for you and the equipment in the event that you accidentally touch two speaker wires together and either burn out your amplifier or risk getting electrocuted. A couple of seconds to hit the power button can save hours of shopping for new equipment or recovering from personal injuries.
Source: Adam