Just tried a run through of a mix I'm in the process of doing, and when I listened back to it, I can hear feedback throughout the whole track (not a huge amount but enough to sound shit!). First thought was that it is the RCA to 3.5mm cable (connecting mixer to laptop) that must be faulty. But I can see no cracks or marks on the cable of any real substance. Went to an audio dealer today and he said the same - didn't even offer to sell me a new one he was so sure it should work. But obviously it doesn't fucking work. I have my monitors set up right next to my laptop but using XLR cables which are balanced and shouldn't therefore be a problem either. Any ideas what else could it be? Should I just go and buy another RCA-3.5mm cable anyway? So frustrating!