Noices on intervals in 000 BD Grand Piano

[diez]

* I have Extreme, and I'm not the first owner of it
* Seems that I haven't changed settings of programs

Problem:
When I use "000 BD Grand Piano" (or some another prog or comb) and play G#4 and B5 together (or some another interval), in headphones I hear some noice after attack. Sounds like some mp3 artifact or so...

When I turn off the tube I hear the same.

Is it problem with settings? Or it's problem of all oscillators in KORG Triton?

Thank you for answer...