Leave them on! Notice how the amp is warm/hot when left on? When the amp was designed, it was always evaluated after it had warmed up. It does sound different after it has warmed up (Not just the heatsinks but EVERYTHING). If it is a big solid state amp, this can take hours, or even days. But even the most powerful amps draw very little power, when left in idle, so don't worry about power consumption.
Leaving Amps on
I am wondering, in the case of which is best for the speaker, is it best to leave the amps on all the time, or shut them off between use. I know that turning them on and off causes heat expansion in voice coils leading to stretching; The main reason that pro audio setups that are permanent stay powered up all the time. But, is it really best? Can I also cause long term damage to the speaker by leaving it powered up with no signal being sent? I just recently read an article that said too much continuous power can burn the parts in the coil. Can anyone help? Thanks in Advanced! Sam