Tim,
KN is correct with an addendum. I used the JBL bookshelf speakers along with the original Tyros speakers and that sounded nice. Although I still have them hooked up I really use my near/close field monitors for all my playing in the studio. The Altec Lansing 621's made their way to my X-Box and play station, where they sound the best.
The real answer to your Q. lies in what is it you want to do with your speakers. If the primary goal is to play and you want the best sound for that, that will take one type of speaker. If on the other hand your goal is monitoring for recording that takes a different type of speaker. For just playing and enjoying the best sound I use my Motion Sound KP200S stereo amp. For recording and monitoring I use M Audio Audiophile BX 5's and when I'm just doodling looking for ideas, I use the Tyros with the JBL bookshelf set up.
In any case you will want powered either monitors or an amp.
Terry
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jam on,
Terry
http://imjazzed.homestead.com/Index.html [This message has been edited by trtjazz (edited 11-29-2003).]