I have a Yamaha RXV630 / B&W 602, 601 AV setup, but now want to go up a notch musicwise. I'm seriously considering getting QUAD 11L or 21L (based on reviews, looks and price). One thing that has me worried is that most reviews mention that a bad system will make the Quads sound awfull. How is 'bad' defined? Is my Yamaha receiver 'bad'? I would apreciate some input here.