In a couple of months I'll be relegating my Yamaha RX-V495 to pre/pro status by tacking on a good quality 5 channel amp something used, like a parasound or B&K et. from e-bay. I was then thinking about the next step. If I had $400 or so to replace the Yammy would I be better with a new lower end receiver RX-v640 or Denon 1604 or an older higher end model like the RX-V2095 or Denon 3801. Let's assume I'm sticking to 5 speakers for now and I don't care about 6.1 or 7.1 or any video switching. I'm thinking mostly about processing quality for use as a pre-pro. what would be better new or used?