Hi David. I'm using a couple of keyboards as controllers: Roland FP-10 and Edirol PCR-500. The thing is that the MIDI transposition occurs during playback, so the keyboard controllers are idle. I think you are pointing in the right direction with the clocking error. However, shoudn't it always play off pitch? In my case its random. Also, what do you mean by the hardware modules being monitored through Sonar? The communication between Sonar and the sound producing devices (Integra-7 and EMU-Vintage Pro) is handled through an M-Audio MIDISPORT 4x4. Thanks!