Cause of Channel Imbalance

Is the channel imbalance the same at all volumes ? If it's worse at low volumes then it's likely a bad volume pot.

Did you try switching the pre->amp interconnects to see if it's in the pre or the amp ? IF you switch the pre->amp interconnects and speaker cables so you're using the L channel in the amp to driver the R speaker and vice-versa then that will isolate whether it's a preamp or amp issue.

To Seandtaylor99,

Thanks. I will try that and see what happens.

Neal

Another possibility could be the interconnect cables themselves. It's happened to me. Turnes out to be an intermitant short in one of the cables. Try switching the L and R cables and see if the problem changes channels