I have Polk CS400i hooked up with Adcom GFA 7605 amp and I'm using Yamaha RX-V1400 as a pre/pro. The problem is sometimes when I watch movies in 5.1 or DPLIIx the center channel sound goes down by itself and then it comes back on its own. Sometimes nothing happens and it works fine.
I have re-wired everything but not sure what is the problem, is it the pre/pro, amp or speaker. No idea!