I don't think you should be monitoring using headphone output of the 2020.

The Audio output of the 2020 should be routed to a Line Input of the soundcard and any monitoring, headphone or otherwise, should be taken from the soundcard's output, otherwise the latency settings and corresponding methods of lining everything up properly that must take place within the BB software can't be heard.

That, and if you use any RealTracks, they will be directed to the same soundcard output.

--Mac