I’ve rented the 515 for the last month while my Kurzweil is being repaired.
I have only played it with my headphones and internal speakers.
It’s not a bad a little unit but I would never buy it as I’m really more focused on workstations. Just rented it to keep my fingers and brain active, I have short term musical memory so can’t go long periods without forgetting songs etc…
I was expecting something richer and more authentic sounding to an actual grand piano but to me, it doesn’t meet the standard I wanted. I actually prefer the ballad grand of all the pianos on board. The Bosendorfer has great dynamics though going from quiet soft passages to harder more aggressive playing, I thought it was the best for classical style music.
I found the keybed enjoyable to play but a little heavy compared to my pc3k, I’m sure I would get used to it.
It’s a very heavy unit to lug around, that’s got to be a factor for anyone buying it.
it also has no user memory and any adjustments you make to customize your preferences can’t be saved as far as I know. I didn’t get a manual with it and really didn’t care to delve into that issue, maybe I’m wrong.
There is a gorgeous pad on board called “lite pad”, I really like that. The elector pianos are quite nice too, I combined the soft and phaser electric pianos to play Billy Joels Just the way you are and thought that sounded very nice too.
Nice keyboard just not for me, I’m sure many will love it.