Is it possible that the room acoustics and positioning of your speakers account for the balance issues? I've found that using spades on my spkr cables improved the overall balance compared to bananas which can loosen up. I've gotten to the point that a preamp without a balance control isn't worth owning.
Pre Amp break-in balance issue
I just got a Luxman C700U pre amp to go with a Sanders Magtech amp and the left channel is weaker than the right. If I set the balance at 9 O'clock I get a balanced soundstage but in the middle it's tilted right. The amp is pre owned while the pre is new. Can this be a break in issue that will correct itself? I checked and rechecked the connections repeatedly. Thanks for any input, Joe.