mixer volume knob is limited to -40db

[jjYBdx4IL]

Would it be possible to change that to complete silence? Maybe through a non-linear scale?

[fundamental]

Generally for controls which effectively map -infinity,finite_max_value in a log space the solution is something like min1,min2,max. Then define the parameter as operating over the domain of min1..max, but if the value is below min2 (note min2>min1), then the value is changed to 0/-infinity/etc. Aka, the smallest value (+ a small margin) are handled differently. I forget if this specific control is handled like this or not. It might already be doing so under the hood.