I too heard that a system should be left on all dayto keep the amp nice and warmed up but.. do you live in an area with requent thunder storms?
I live in Berlin, we get them all the time and at short notice. Was in my local hifi shop the day aftera nasty one last week, talking about the subject of fryed equipment when a guy came inwith a cooked Arcam amp - ouch! Turning it of at the switch does not help or with a power board with a switch, the chrge will jump right over the switch and into your beloved gear.
So now, i pull the plug and when i want to stick in a Cd, I warm the amp for 20 mins or so. Maybe a pain in the butt - better than cooked gear.