Many thanks for answering! And sorry for my being absent in this thread for too long.
I was talking about the same setting for all-channels, like in Korg PA global setup. The idea is that the user can pick a tuning preset from a dropdown list and then select the base note to which the tuning is applied (e.g. "Kirnberger | C"), or create a custom tuning by entering +/- numbers for the twelve notes.
As for the UI, maybe a "Tuning" button can be added somewhere to the left of the "Mixer" button. It could open a popup dialog with the following elements: 1) a dropdown with preset names (Equal, Pythagorean, Werckmeister, Kirnberger, etc.) 2) a dropdown for picking the base key (C, C#, D, D#, ...), 3) twelve per-note deviations in cents in numerical edit boxes.
Here is a link to the reference table of temperaments with per-note deviations in cents:
http://www.instrument-tuner.com/temperaments.htmlThese can be used to initially fill the dropdown:
Equal Tempered, Perfect Octave
Equal Tempered, Perfect Fifth
Just Tempered (Schugk)
Just Tempered (Barbour)
Pythagorean
Meantone
Bach (Kellner, Well-Tempered)
Kirnberger II
Kirnberger III
Neidhardt I
Neidhardt II
Rameau
Werckmeister II
Werckmeister III
Other presets can be added by the user if he wishes so.
Thanks again for reading my post!