well, the interconnects I use are all of Outlaws top of the line non-balanced cables. Switching them would seem like a good idea, but for one, Outlaw (since they make both the cables and 990) has made it very hard to remove the cables esp. since they have the ends which require "screwing" in a bit and second, I am pretty sure that this comes down to a cable in the CABLE box because when it is unplugged, the hum goes away.