What is the maximum recommended distance that an rca cable can be run before any issues may arise? Reason I ask is because I'm considering purchasing some powered surrounds and a second sub and my avr has only unbalanced outs. So, I'd have to run an rca cable about 30' for one of the surrounds, 50-55' for the surround and 50' for the sub. Well, I'd probably run xlr cables in-wall but it's not like that would make it balanced. I'd really appreciate any advice on this subject.