not wanting to pull out the notes from circuits last semester, but line freq. does change how the caps are charged. the big power transformer and capacitors and inductors in your amp will store charge so that you can drive it above what you may calculate as the max power coming out of your wall. they will also act like a damper in the system to limit the speed with which the current is supplied to the amp. I have built devices that i did not feel like putting a battery in, just use a capacitor, it will supply a charge like a battery. ( if you use the right size and the circuit is designed for it) now, what this has to do with the OPs question i have no idea.
CV's are not great, but they work and do a decent job. Yamaha amps are not the top of the line either, but i would put them up against a comparable HK or Dennon any day of the week. I think a receiver with a bit more power would be a good upgrade for the OP. No matter what an upgraded receiver will provide him with more features to make it sound like he wants it to. It will also give him more options if the current one has no pre-outs or a LF-out. If he is looking for cleaner more refined sound an upgrade in speakers may be just the ticket.