My understanding, is that what those amps are having trouble with is "clamping" as part of your DC offset. I had an amp a couple years ago that displayed what you're describing, at power-off. On 2 sets of speakers I had at home, it would cause the drivers to "suck in" at time of amp power-off. I chose to get rid of that amp rather than repair, and switched to a Bryston. Maybe you can call or email Bryston to confirm there's a problem, and send in for repair.
