I Need An Outboard Balance Control, Do They Exist

I have been using both Classe and ARC pre-amps which have built in balance controls. I recently purchased an integrated amp that doesn't have a balance control. I need one since I have my left speaker (Eminent Technology LFT-Vlll's -dipole) in a corner where the right speaker is along the same wall but not in a corner. I cannot do anything about this set-up. It has sounded fine with the above pre-amps because of my being able to adjust to equal volume from both speakers using the control. The sound from the left speaker is louder due to it being in the corner. Is there an outboard balance control that I could use through the tape loop or does anyone have another solution for me? Any ideas or information would be greatly appreciated. Thanks in advance. Bob