I have been using Denon 5.1 receiver and Klipsch Synergy Speakers (KSF 10.5 main )watching DVDs for years. Now I start to think about adding an Amplifier for listening music. I am a good ebayer with $500 budget. Anyone can give me some advice about what to do? because I have little idea with amps and how much improvement for music I can get with $500. Thanks in advance.