Not sure if it is your case, but I had some buzzing with some of my custom preset.
Found out that it was possible to cure it by reducing volume of the particular buzzing instrument with A + Vol(-)
Interesting part is that reducing overall master volume did not remove the buzzing.
Looks to me that some clipping might occur on the particular instrument output, before master volume is applied.
Well, I didn't know about that approach to adjusting the mix - so that's awesome in any case.
Sadly, though, it does seem to be more about the general volume of the instrument (I looked it up, it was the chord patch called Bedroom). Support suggested it might be the haptic motor vibrating (passively to the sound), and this seems likely, as a similar noise happens when the haptic motor actuates. Adjusting the chord volume just changes the level of the master volume where I hear the buzzing...
And the buzzing is rather loud relative to the sound at higher volumes. So, it's pretty limiting.
Davclark
Do other folks hear buzzing from the orba on some sounds? For example, even at moderate volume, grapefruit causes buzzing on some notes.