I think the BK9 sounds pretty good with no compression and no EQ at all. And any settings that I use would be of no use to you, you don’t use the same PA I do, you don’t use the same speakers at home I do, and your room is undoubtedly different to mine!

Your ears can be your only guide, and comparison to well recorded CDs.

The dynamic arranger seems to have a bit of a “window“ of velocity recognition. In other words, if you play a really loud note then a really quiet note then a really loud note then a really quiet note quickly, the volume of the affected parts (or more accurately the velocity of them, the feature doesn’t work on the part volumes, but on the note velocities) doesn’t yo-yo around. I have never done any testing, but it feels like maybe there is about a couple of beats or more worth of analysis before you get a change.

I would suggest playing around with the feature and listening to what it is doing! Five minutes of listening is worth an hour of written explanation!

Finally, as to thinking the left hand of the piano sound is “low“, I would suggest going and sitting at a real piano. You will quickly find that a real piano’s bottom end is not fat like a bass guitar or an upright bass but so often keyboard players EQ the low end so it sounds artificially full. But that is not how a real piano sounds! I have played on 9 foot Steinway D pianos where the bass is thunderous, but it still isn’t like a bass guitar!

Networking, and finding people around you that have the “real deal“ and getting a bit of sitdown time on them will help you enormously to avoid the mistakes of artificially hyping the sound of real instruments. Play a REAL piano. Play a REAL Fender Rhodes. Play a REAL Clavinet. You will often be surprised by how they are not designed to be full and fat over the entire range. There is a reason that bass players still have a job!

Finally, playing a piano sound on plastic keys ALWAYS compromises the sound. The dynamics of moving a chunk of wood around leads to a much more pianistic performance than tickling little pieces of plastic! If you get the opportunity, pick up a VERY old digital piano with 88 wooden keys. It will not sound very good, but if you MIDI it into the BK9, you will be amazed at how more alive the BK9 piano sounds.