I think there is nothing wrong with having a volume control, as long the circuit is properly designed. My power amp has one and the manufacturer said some people prefer to not use a preamp, so they are glad to have it. His design is such that if you use a preamp, as I do, and wish to eliminate the amp volume control, to turn it all the way up. This effectively removes it from the circuit. I can verify this as there is a noticeable difference in sound if I don't turn it up fully, it is then obviously engaged. Even though I don't normally utilize the volume control, I am glad to have it as there are some recordings which sound better when I do use it.
