I have a Yamaha DSPAX761 receiver and Wharfedale Diamond 9.1s for the front speakers. I've wondered how much getting a music amp would improve things when playing CD's. I don't actually know how it would be connected though. I've heard about pre-outs but don't really understand it. Could I use a normal music amp or would I need a power amp? Any recommendations to match my budget system would also be appreciated.