Originally Posted By: Hellcommute

The difference and what everyone seems to ignore is that the capacity of the transformer to provide the current (VA rating) is of high importance-- and often cost.

This is pretty much the only rating that i looked at when i was buying amps... My large stereo amp has the below spec's..

3000VA with a capacitance of 40,800µF per channel.

Considering the cost of copper nowadays... Yes, the power trasformer can be a Huge part of the overall cost.