I have tried out the QSC PLX3602, and the XTi series amps, but my Adcom 555II blows them both away?? The Adcom is a power house that I now use on my gigs. I bridge them both and the do a ez 650watts@ 8ohms and 900watts @4ohms they have played awesome each time never getting hot stayed very cool and never once shut off, and the SQ is so clean!! So why should I stick to QSC or Crown that cost three times as much??