Oh, ok.
I follow, I assume your using one of the typical 48/60-in-1 Jamma boards?
If so I know what your taking about, adjusting the volume is a real b**ch!
I have several boards like this.
I don't know if I missed it in the thread, did you post links to where you got the parts ?
I never thought of that audio solution, but I like it.
Lastly if I may ask, how do you wire it ?