does amp draw alot of power when volume is zero

If you are worried about wasting energy, and money, on idle music systems you should consider Class D amplifiers. These amplifiers are very efficient in use and at idle. My desktop integrated amplifier draws 15 watts at idle and sounds great.

For those who are actually curious, spend the 25$ on a 'kill a watt' power meter.

This meter will not only give you line voltage, but current, watts, VA AND therefore powerfactor.

A cheap test and part of my standard kit, though never left in system for long.

http://www.p3international.com/products/special/P4400/P4400-CE.html

Thanks for all the suggestions. Mine is a class D bel canto, fairly cool at idle, just a couple of warm spots but certainly not hot.

With a Class D amp; the output devices are turned off(no bias), until a signal is detected= high efficiency/low temps/low current draw at idle. Class A has full bias applied to outputs, ALL the time= low efficiency/lots of heat/high current draw at idle.