When playing live, I've never been happy plugging my digital pianos into house PA's, or even my own PA (Crown Powertech Amp and 2 JBL 15" speakers). The resulting amplified sound is certainly loud enough, but the tone is flat, one-dimensional, and excessively strident in the treble.
I have a theory about DPs, it's that almost all of them are not set up correctly for public performance. They are designed to sound best to the pianist, not an audience.
Listen to the left and right monitor speakers as you play. The bass sounds will be on the player's the left. This is totally un-natural for an audience. A live piano is always set up so the side
of the piano faces forward and the audience only hears the treble stings after
the sound is reflected off the open lid.
When you connect the DP to a pair of good PA speakers those speakers are playing back samples that were recorded with mics placed under the lid of a grand piano So the sound you are progesting into the room is what people would hear if they were to put their head under the lid of a grand piano. No wonder EQ, compression and what not is needed
What would happen if you place the the stereo pair of PA speakers 5 feet apart with the "left" speaker directly behind the "right" both facing the ceiling. Then suspend a large sheet of thick (2") plywood angled over both speakers so as to simulate an open piano lid?
This would create an approximation of the speaker geometry of the Yamaha Avent Grand. The idea is to place the PA speakers in about the same place as were the sampling microphones and then place them inside a simulated piano case. From this point you are dependent on the hall's acoustics to project the sound. You hope they have it set up right.
I've just started somo simple experiments and so far have convinced myself there there is a potential for a huge improvement in sound by using special built "piano speakers" rather then general purpose monitors. I think the N3 is a perfect example of this.
I have a long term goal to build a speaker that looks like a table with folding legs. You'd set up the table on stage near the keyboard then it would have a lid that opens like a grand piano to expose some speaker drivers. I'll get there in a series of small steps. I have a couple simpler ideas to try first