Quote from Stéphane on 21 January 2020, 13 h 45 min

I propose here a small and very simple hack to have the + 10V coming from the buffer (when it is empty) directly in the attenuator stage.
(after this mod, if you plug a jack into the attenuator input it bypass the contact)

Be careful!
this modification is at your own risk. If you make a mistake, you may risk damaging the module. You are responsible for what can happen. From the moment you work on the module circuit you lose the warranty.

It's extremely simple: you just have to unscrew and remove the first PCB and solder a black or a red or a yellow or a green or a brown... no not brown, or a blue or a pink or a purple or a grey wire between the points indicated and thats it!