I have owned the Parasound HCA 2200II for several years now. It was a big improvement over my Adcom 545 II and my brief encounter with the 555 II. I had a 545II for a long time and wanted a more powerful amp when I moved into a house with a big room. I bought a used 555, but while that transaction was going through, I found the Parasound, and bought that also. The Parasound was much more powerful and much more revealing than the Adcom's. Playing some concert Laserdisc's that I was familiar with revealed a lot of low level sounds that I never heard before, because they were buried by the louder stuff and muddied with the Adcom amps. So I was very satisfied. As I was shopping for $8K-10K speakers, nearly everyone that asked about my amp gave me a disappointed look, so I feel that perhaps I am missing out. After the speakers I will be shopping around for an amp to see how much better it gets. I imagine that there are many amps that would give me the same step up in quality that I noticed by going from Adcom to Parasound. It is a great bargin as a used amp, plenty of power, good quality for the price, although I'm sure there are lots of better sounding amps, but they are probably a decent amount more expensive.