"Tools/Global/Adjust Minimum Attenuation" seems to ask for a number. Then it changes the attenuation of all instruments equally, ensuring that the minimum attenuation is equal to the selected value.
The problem here is that it assumes that empty fields are 0db attenuation, and fills them out with delta-attenuation. This is incorrect, as they actually inherit instrument-global attenuation. Let's say 20db of global attenuation, delta = 10db. The proper value is 30 db, but Polyphone fills out 10db.
The solution is to leave empty fields blank (inherit), except for instrument-global attenuation (you should move "starts-from-zero" from instrument splits to instrument-global).
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Also can you add a feature for "attenuate entire soundfont by fixed amount", instead of "minimum attenuation"?
That's probably a good idea as well. Also you could catch negative attenuations, and possibly alert the user.
Preset-level volume tweaks allow you to add negative attenuations, which reduce instrument attenuation. This might be useful for soundfonts with large preset attenuation.
However, they silently break (stops at zero) if you move below zero.
So the Tools/Global/Adjust attenuations forces me to attenuate instruments below zero. I guess that's the right thing... Negative instrument attenuations explains why Timbres of Heaven was so loud, and clipping so easily.
Sorry I don't understand the fact that it "forces" you to attenuate instruments below zero. But while I am reading again this thread I am thinking that I didn't implement the warning display when a computed value at the instrument level goes below zero (this would result to a zero anyway).
