I'm looking to replace a cheap amp I'm currently using for my setup. From my research, I've narrowed it down to the Denon PMA-600NE and the Yamaha A-S501. Out of these two, it seems the Yamaha would be the better choice. However, I've just recently acquired a Rotel RB-850 for $15 dollars, and it seems to be in good working condition. I've tested it out and I am happy with the sound. But, the RB-850 is usually connected to the RC-850 pre-amplifier, which includes the volume control knob, bass/treble controls, and all the inputs. I don't own the RC-850, but on ebay I see an RB-850 and an RC-850 being sold together for around 300 dollars. I've found that you can use two RB-850's to power each speaker separately using a mono bridged connection (although I'm unsure what a mono bridged connection actually is, or if I'd even want to go through the trouble of setting it up). So, my question is whether I should go with the Denon PMA-600NE/Yamaha A-S501 or purchase the RB-850/RC-850 off of ebay to go along with my already purchased RB-850. If it helps any, I'm currently using a pair of Onkyo SKF-530F's, and I mostly listen to music with a Technics turntable and Nakamichi cassette deck. Thanks so much