Don,
I doubt the difference in sound was caused by "tweaking" concerns. While I had the BK-5 I used headphones, played with the built-in speakers, ran it through both of my Bose Compacts and nothing made a big difference in regards to comparing it to the BK-7M I owned. The BK-5 simply did NOT produce the same quality sound as the BK-7M. Now that I know how to properly use and setup a midi controller I am thinking about buying another BK-7M.

Deane