Slim, let's compare notes on the gut punch mode after you've received your sub.
CDs have a 20 to 25 dB greater dynamic range than vinyl. You may be reaching the limits of your amp. One channel could be slightly different than the other. Another possibility is the impedance of the speaker. Ask Bryston what the T's impedance and phase is up to and above 20 Khz. It could be that the CD along with the program material you are listening to is full of ultrasonic content that is taxing the amp particularly if the T's impedance dips below 4 Ohms and its phase deviates extensively from nil.
It's also possible you've cooked one of the Ts and I am sure no one ever thought that would be possible but by your own admission, you've been pushing them to the spec'd envelope.
