When Hugo demoed the MK2 prototype for us in San Jose, I don't remember whether there was a function assigned to pressing and holding the rotary knob. As it stands now, I think you can press the rotary button to enter the menu structure, but I don't think there's been a function assigned to holding it down. Since the other four buttons all have alternate behavior if you hold them down, it would make sense for the rotary button to have something similar.
Hugo, did you have any plans for this function? If not, may I make a suggestion? (And I'm sure others will jump in here with their suggestions, too.)
How about making that go to bass/treble/fader/balance? I know you haven't implemented bass and treble on the DSP yet, but this could be your excuse to do it.
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Tony Fabris