Hey schwill - I think the concept would remain the same. The idea behind running the ADC high is because to run *most any ADC but all the way up is actually introducing an attenuator to the full signal. So it would be a cleaner signal (less electronics or noise introduced) to run the ADC high.
My advice would be to run your minidisc level high, not quite all the way up, and work from there on the mp2. Leave a little room to play with on the minidisc if you can for more options (if the mp2 knobs are too touchy at a particular level or something).
HTH
*I understand the SBM1 to be set at neutral at 5 and gain and attenuation above and below that. Most are neutral at wide open.
edit: i think, i've heard, i could be wrong, someone else can correct me, various and sundry other qualifiers to the above info, as always...