Driving my Radia 520i amp (an Odyssey Stratos Plus) into clipping would destroy the 520i. To be precise, the ribbons would catch on fire. Granted, that's different than the sub, but if the sub test tone is so loud, I'm concerened about the others.

I had followed Outlaw's recommended manual procedure for balancing the speakers, using my own test tones and noise sources (not trusting the level of the 990s), and calibrated the absolute level to THX levels at 0 dB on the 990 (padded down 8 dB actually for L and R).