If you read the 2000 manual carefully there is no mention of a stereo mic but very strong indications that it is mono. I suspect that it is similar to the 740. This has a 'stereo' jack in that it has tip, ring and sleeve. However, the sleeve is grounded, the tip is input and the ring is open but has a switch to ground and shorts the input until a plug is inserted. There is a single mono amplifier with the mic setting giving a gain of 5 over the line setting by inserting a further amplifier stage. I have a genuine Yamaha Vocal Harmony mic (an Audix) which has a balanced XLR connector but the cable has a mono jack plug on the other end. The cable connects one side of the mic to the sleeve. So the connection for any mic is unbalanced with the tip and sleeve as the conductors and the ring doing nothing.

Bryan