I always do a sound check with recording of myself, and adjust as necessary ... and if there is someone in the audience whose 'ears' I trust, I will ask them to listen and let me know how it sounds ...
I love to hear myself through the KB monitors ...

Different folks ... different strokes ...

Here it is in a nutshell. My "sound" consists of the combination of my voice, and the music that accompanies it. I create that blend in my stage space and the total combination of tones covers a small, 6-10ft area directly in front of me. In some rooms, that's all I need to cover, but for most others, I need to reinforce the sound throughout the room. Yup - that's why it's called sound reinforcement.

It's pretty simple, really ... I have one sound pressure level at the point of origin, and a mix of that sound that is fed into speakers that project the sound further out.
If I turn off the main system, my coverage is minimal, but it's balanced to please me, and hopefully to please the audiences that have hired me back for 50 years.
(first paid job was 1969, but had bands a few years prior)
When the sound of the room itself, is louder than my stage area, I need to turn up the main PA to fill the rest of the room, and many times I need to readjust that level more than once. The room has an ebb and flow ... a tempo, and an energy that I orchestrate. Volume, and presence are tools that I use to accomplish this.

The idea of monitoring from a tower behind me doesn't allow me to keep my sound "in my face", so I rely on that "up close" on stage presence to keep me honest. I am constantly aware of the room sound, and level, and I check and modify it as needed.

Every room is different, and ever performance is different, so I minimize the surprises by creating my "sonic bubble" to reside in ... during work hours. Works for me, cuz they keep asking me back. Not changing a thing.

With my old band , I switched from the Roland Prelude to the BK5.(Small footprint of the keyboards).
The Prelude definitely did sound better then the BK5 (from the built in speakers).
The BK5 did have a thinness to it.(most likely eq'd to allow the speakers handle the sounds).

It reminded me of older times using Roland JP8, Junos, and JX10....switching to Roland U20 . Thin sound was evident, but the samples of U20 were great.

The E-A7 is worth the difference in cost over the BK5.

It is worth mentioning the BK5 does shine when set up with a mixer and decent sound system... On stage it lacks nothing in the sound department. My old band still uses the BK5 and they sound great(even without me)

I also did not like the jog wheel on the BK5( I don't like the wheel on the BK9 also).
Navigation and features are so much better on the E-A7.

Thank you Fran for clearing that up
I was think along those same lines also..