The GeoDisc should be here this week. I'll try as Soundfield suggested and first play other SQ records through SQ, then QS and bypassed. I'll try some CDs but I don't have many. I have a tone generator and scope, I guess I'd set it to SQ and do a spot check at 10 or so frequencies 20-20K (or 40 to 15K, It ahould show up there and be easier to hear) comparing a flat input to any output? Or just the fronts? I'm guessing you mean it should be any of Rf, Lf, Rb, Lb. I wouldn't mind checking it. It is so great at QS/simulated that I'm hesitant to want to ship it. I'll report back on the tests, might take a while to clean off the bench.