Keith welcome, and this is one I never heard before. I don't use the Avia disc and I can't imagine any problem with it that would send the sub calibration tone through both the sub and the mains. As you indicated, when you set THX yes on your 777 that should automatically set the sub yes, the speakers small and the crossover at 80Hz, which is what you want. Take Avia out of the picture and calibrate with the 777's internal tones; any difference? If not, set THX no and manually set sub yes, all speakers small and crossover 80Hz. Very mysterious.
