Disklavier

Can I improve the sound quality of the accompanyment on a symphony capable 
Piano Disc  system  PDS 128
I understand that the later generations of the 128 have a better sound card 
than do the earlier models.

Also. to accomplish the same purpose rather than replace the existing c ard 
with the later one,could I use the "midi out" from the control box to improve 
the sound quality and if so how can the piano part on track one not also be 
audible through the speakers in addition to the accoustic piano part.

Any responses can be sent to me privately to meyerifkin@...

Thanks

Dick Meyers.