donny...
Stereo input devices can run thru the PSR2K one of two ways:
1. 1/4" Mic/line input set to line.
2. RCA jacks inputs.

Why the Stereo mic cable doesn't work still baffles me, as well as the folks at Monster.
Based on Mike's diagram I see no reason why it shouldn't work...but I tried it on two different boards and it will not take the mic signal.

Eddie