houston, we have stability
Well, with the power of the web, various BBSs (including osx audio and the DUC, my ProTools system seems to be stable and noise-free. I still don't have the 002r working, but I have a very sano setup. I am using a MetricHalo ULN2 interface for both A/D and D/A, thus avoiding the rather weak converters in the MBox.
So the setup goes: source inputs into the ULN2, which sends converted digital signal via spdif to the MBox. This just passes the signal on to the computer and ProTools. Then I take signal back out for monitoring by spdif out of the MBox, into the ULN2, and have my Adam p11 speakers connected directly to the ULN2. Very short signal paths, very good A/D-D/A, everyone's happy. So far.