hmmm. Playing only with our ears hitting the keys would certainly be a challenge & more likely an impossibility.

Music theory explains the scientific (mathmetical) principles behind music and can help become better musicians. Yes, I agree that the bottom line in making music is what is played, heard and appreciated listening thru our ears, but understanding the theory behind the music can only help us in that process.

This emphasizes my point regarding adding those' left hand' voicing I outlined above. Only with these can you attain this unique 'sound' HEARD playing by ear (thru our ears ) when playing in arranger auto accomp mode. The 'on bass' feature is certainly useful as well, but is an entirely different animal, and does not provide the same results heard.

Speaking of Mark Levine, he was actually my piano teacher, and I had the privledge to study with him privately a number of years ago. It was him that taught me the rootless jazz chord voicings outlined above. Ok, the chord voicing above are not EXACTLY the same as the II-V-I A/B voicing outlined in his book, but they are still, based on them, abeit (less one note 3 note vs 4 note chords) that Technics, Yamaha, and Ketron implemented to accomodate the limitations of the arranger chord recognition table. They still though, preserve that open chord voicing sound that is so the signature of piano jazz and an important supplement to include in an arranger keyboard chord recognition table. For those interested in checking out Mark's Jazz Piano book: http://www.shermusic.com/jazzpno.htm . Be sure to checkout the chapter covering A/B chord voicings. - Scott