I couldn't agree with Gary more. You have to sing with a pure voice, as little vibrato as possible and directly into the mic without overloading it. It requires practice, but I get great results even on the S 950. After awhile it becomes automatic. Just keep working at it.

PSR S950, PSR S900, Roland RD 700, Yamaha C3 6'Grand, Sennheiser E 935 mic, several recording mics including a Neuman U 87, Bose L1 Compact, Roland VS 2480 24 Track Recorder
Joe Ayala