Your question seems to suggest that there is nothing wrong with the DS88 piano at home, it is the PA where there is an issue. so the issue is clearly with the PA speakers. So why are you now looking for a different piano sound? It seems to me that you should be looking for decent PA speakers, as that is where you point the problem to be..... How would we know what piano sound would be good with the PA speakers that you have when you haven't even mentioned the PA speakers that you are running through. For all we know upgrading the piano sound might sound even worse with the PA speakers. My suggestion is to fix the cause, not the effect.
Not sure where you 'position' these speakers in relation to where you sit/stand during the performance. Try moving the speakers about 20 feet away from you and turn the speakers toward you simulating the effect the crowd would get when listening to you. See how they then sound to you 20 feet away pointing at you, this is how they would sound to the crowd. Make your adjustments and see if you can get correction. I say this because in one of the bands I play in (I play in a few believe it or not) the two guitars players play acoustic shows independent of the band full 5-piece. Occasionally I join them to make it a three piece acoustic. Acoustic shows they use a Bose Line Array system. Out in the crowd (20-30 feet away) everything sounds great, pianos are balanced (one of the guitar players also uses a Korg SV-1 when they do acoustic and I just use his setup). When I come up to the stage and play it sounds like mud, no definition to the sounds and almost sounds as though someone took a blanket and put it over the line array. This phenomena is consistent at different venues, sounds clear out front and muddy on the stage. That is why I'm suggesting you move the speakers about 20 feet out in front of you and then turn them toward you. This gives you the 'crowd' effect and how it sounds to them. See if there is a difference between what you think you hear on the stage and what you actually would hear out front. If there is a large difference between the two then and it actually can sound decent out front then it is more of a positioning situation. If you can't get it to sound decent with them 20 feet away then those speakers are probably not what you are looking for in order to use them as PA speakers projecting acoustic piano sound.
reverb.com
I also have this same issue. My Korg PA1000 piano sounds bad through my Bose L1 compact. Not quite as bad on my Roland KC-220 keyboard amp (for small gigs). But, there seems to be a vast difference in piano sounds between the keyboard speakers, monitors, headphones, and PA systems.
Nord stage 3 or elektro 6hp
I seem to have the same problem with any keyboard that i use. They sound great with close reference monitors, or headphones, but tinny when going through a regular PA. I've kind of narrowed it dow to those plastic case self powered PA speakers. There seems to be some sort of nasal mid range sound out of those speakers. However, I found that when the cabs are mad of wood, that sound seem to be lessened quite a bit. I think that the QSC KW series might be the best choice. They are expensive, but do sound better than the plastic shell speakers.
I agree that wood cases sound much better than the plastic ABS. I guess some people will trade quality for lighter weight. Not my style.
I'm a fairly new RD2000 user however, I'd think the Editing options are about the same for the Juno. Click on Edit, then Key Touch, and then at the top, switch from medium to light touch. The sound is a much fuller, crisp sound.
Try adjusting your EQ to take out some of the upper midrange and treble frequencies in the 4K-8K range. You may want to try using a small mixer to premix your keyboards.
