The two knobs at the extreem ends of the units front panel have gotten wacked and dont work correctly. The one on the left can be made to work by pushing left on the knob ( and holding). The one on the right turns very hard and right channel does not pass signal. The sub out is fine if the left channel is driven. The front panel " mute" and "invert" push buttons are quite noisey. I think if you fixed these items it would all work fine