Mine are very soft too - didn't notice any distortion though. I ran them though my external KB to try different piano patches and they are still very soft. On the other hand, the Jazz Piano 1893-1900 are much louder by comparison. Not knowing much about Midi, I assume it is in the recording process. I was surprised to hear such a big difference.

I hope someone chimes in with some hints about this.

I think if you compare the Kenny Barron ST to RT, the soft sound is found in both.