I know you asked Roger but I happened to be awake (it's great having a holiday off work!).
In my opinion (and it answers your question I reckon) the absolute first place to start in setting up your KN7000 is the Equalizer (Page 163). This will deal with your overall mix preference and the bass sound you're discussing here.
The second place to go is the Expand Mode Filters (Page 67).
The Third place to go is the Custom Panel (Page 23). Keep working with this button until it has everything you like best saved in it. Don't be tempted to set it up as a simple piano, it's easy to get a piano. Save your favourite settings for absolutely everything in this button and thereafter use it as the basis for your future registrations. The Custom Panel does not get overwritten when you Load things.
I use my KN7000 through a Roland amp or a 5 speaker Home Theatre System that my son kindly got me for the purpose (it has a sub-woofer of course and can play CDs, you can pick them up for a song). You are also able to send different Parts to external speakers than through the KN7000's internal speakers should you wish (most people don't realise that so I keep mentioning it