Scott,
I tried that combination with my PSR-550 and I think it sounds really good. I know some may not like it on the PSR-2000, but with the PSR-550 it really makes a HUGE difference in my opinion. I did a little tweeking (although limited by the 550's editing choices), and it sounded great.. I think it worked well on the 550 because the 550 doesn't have anywhere near the speaker quality of the 740 or the 2000. I think one of the biggest let downs with the 550 is the bullcrap tweeters they put on it, and claim they work... To those who don't know, the PSR540 and 550's tweeters DO NOT WORK.. They are just for show. If they actually worked it would be obvious change in the sound. I have a pair of the Roland Micro Monitors, and when I hook the keyboard up to them it makes a world of difference... Maybe down the road Yammie will fix this....