Then the logical conclusion imo Eddie is a defective Mic/Line In Jack on your PSR 2000. As I stated earlier I run a "stereo", ie., TRS Monster Studio Link cable into my PSR 2000's Mic IN Jack from my Rolls Phantom Power Adaper and mine works great with my Shure Beta 87A. I think with all of your detective work with still no resolve to the problem, that a defective Mic In Jack on your PSR 2000 seems like the logical conclusion and where all the arrows tend to point to. If your PSR 2000 is still under warranty and you can spare to be without it for 2 to 3 weeks (God forbid, right?), ie., ["Should I send it in? No, I better not. Can I do without it? Let me see, did you say 2 to 3 weeks? No, I guess I'll just live with a defective Mic In Jack and use a Mono cable instead. But it sure would be nice to have everything working right on my PSR 2000, especially when I sell it or trade it in. Well maybe I CAN do without it for awhile. I'll just go to Guitar Center everyday and get my Keyboard fix there. Nah!! Guitar center is too far away! Oh well, I'll just stick to my original plan and let Monster Inc. take a perfectly good Stereo Cable and turn it into an inferior Mono Cable. Decisions decisions!]

Don't mind me Eddie, I guess I just had too much coffee this morning. You do what you want.

Best regards,
Mike