Two other things:

1) The title of the thread is a bit misleading, as I don't think that bypass mode is really applying bass management. It may be using pieces of the algorithm somehow, but it's not as simple as saying BM is still working in bypass mode, as crossover point and other settings are still irrelevant.

2) Although bypass mode should mean no A/D/A, I'm very curious to know in what domain my rolloff issues are occurring. I would not be surprised if it were happening digitally, as I wouldnt' expect the 990 to have filtering implemented in analog circuitry (I could be wrong, but I don't see a need for analog filtering).