Dear All, Wonder if I could get a bit of help please ? Recently upgraded and got myself a second 500r and some B&W 802's so now going to bi amp front three channels . So I've set up everything and wow ! Except one little problem , I've got a 1/2 buzzing/ 1/2 hissing coming out of the tweeters. Not loud but there and gets louder as you crank volume. By turning bits on and off like processor and other 500r i have narrowed it down to the 500r that powers 4 rear channels and 1/2 of a centre. I can turn everything else off and hiss is still there. So I reckon its a grounding problem. Why you may ask? well its the only thing I know of that makes this sort of issue. My problem is that I nothing at all about electrics , absolutely nothing. I should point out that the tag goes into an isoteck vision which then connects to plug in wall. Any ideas much appreciated !