I have experienced this issue too - the choppy audio with the DSP's cycling through PCM 88k, PCM 88X, Data NL.
As an intermittent fault - I didn't hold out too much hope for a quick solution, however, Meridian resolved this very quickly.
Their description on the return note was:
USB IDC Header Cable F/F
MC200xxxxxx was repaired by replacing loom.
As such, it would seem to be a simple cable fault requiring replacement - would of thought it would be fairly easy for a user to fix, assuming it is a standard cable available to source.
I've had it back 10 days now and the issue has not re-occurred.
Matt