I think you'll find the PSR-550's voices to be slightly of better quality than the PSRK-1. Also the PSRK-1 does not have a pitchbend wheel. The 550 has 8mb's of sound memory, and I believe the PSRK-1 has 4-6mb's... Yes the tweeters do not work in the 550, or the 540, and the 350, and 340 as well.... The tweeters are there just to make the board look better. I wish Yammie would not have done that. Tweeters would really bring the sound out more on the 550's internal speakers. The DGX 300 and 500 have pretty good sounds.. I think the piano is better in those models than in the 550.. If I remember correctly someone said in a post some time ago that the piano in those models is the same as on the 9000 Pro.... Not sure if that's true, but I think someone posted that a while back. I've never played the 9000 Pro so I can't truly answer that one The 300 and 500 also have some sweet voices. However the drums in the 300 and 500 are not the same quality as the 550. I know both those models have tweeters, but whether they work or not I don't know... When I demoed them in a music store it was pretty noisy at the time..... What's the price of that new Roland?

Squeak