If you Import your UserTrack wav files into a Biab SGU template it makes them into a big 32bit wav file no matter what Biab is set to, when Biab generates up the UserTracks the playback is just distortion.
This is a recurring theme and has been report many times before.
Biab should automatically convert the 32bit wav to 16bit when a 32 bit UserTrack wav is detected.