I think it is the G61 also. The main channel is my left DSP33 but only getting sound out of the right speaker. I changed out a spare DSP33 and no difference, only the right speaker works. When I turn the volume on the G61 the one right speakers volume stays the same volume. Everything looks good on the front panel. I had my configuration on my laptop and store it again. No help

As an aside, I did have an electrician out installing the DSP420's. Maybe he fried my processor. I can't even test them as I need a midi(s) to SPDIF 6" cable for one of the DSP420's.

G61R, HD621, 3xDSP33 (front, center left), 2xD1500 subs, 2xDSP420 (rears), Sonos everywhere.