I agree that all things being equal, with the bigger power supply afforded by the increased room, as well as less modulation between channels, monoblocks will sound better. However, I have some Essence Emerald III monoblocks and an Emerald II stereo amp. The monos have a bigger power supply but the stereo has a much higher bandwidth. In my system the stereo sounds better IMO. So in this case the circuit design trumps the larger power supply.
