Hi Stan,
Not sure if I quite understand the setting. The SD2 does not do anything with audio files, so if you're using RealDrums (or any RealInstruments) these .wavs must be merged with the SD2 .wav-converted midis.

I guess you could feed the SD2 .wav into BIABs audio track, mute the midi-instruments and have RealDrums play alongside. However it is simpler to use Powertracks or RealBand for such work. Dunno if this made sense...

- Jepster