Well, there's a school of thought which says that audio equipment should warm up for, say, 15 minutes to reach its optimal operating characteristics. In this case, you might prefer that your amps come on and stay on even when you're not playing anything yet.

There are also some people who believe that power cycles on things like amps are hard on them, so even if you're listening to a stereo source you don't want your center and surround amps to turn off.

Speaking of auto-on, how long are people finding it takes for the amp to decide there's no signal and go to standby mode?