After recording from a CD player, I play back the recording using "sync" as usual. During playback, the left channel is clear and the high frequencies are clearly heard, but the right channel sound very bassy lacking high frequencies. I suspected the recording head because the head has been aligned correctly and the calibration done. So I interchanged the brown and black wires from the left recording head to the right input board and the right recording head wires to the left input board. I interchanged the wires and now, the right channel sounds clear and the left channel sound bassy. My conclusion is that the problem is with the recording head and not with the individual audio boards. Now need some advise and guidance whether my conclusion is right.