That's a really nice unit, with all its bells and whistles you would really want to feed it with the cleanest audio signal (raw audio) you can so you don't have to remove any white noise. I see it takes both pre-amp and speaker level inputs, you would use the speaker level output on the FGs for this. The mod I'm looking at doing may be a good way to get a (much) clean(er) output? Then use that device's settings to shape the sound as you like it. It wouldn't matter then if what is lost in this mod is what the new unit gives you in a better way.
This is what I'm thinking of doing this long weekend (ah, a Canberra public holiday).
I've circled where the wires & capacitors would go between:
I've got all 4 inputs to the amp isolated and ready to solder:
Unfortunately, this is the radio from another car and isn't paired with mine. I'd really like to keep mine stock and in storage. Does anyone know if Forscan with the HS/MS manual switch can re-program the ACM on a FG2? I've got the elm327 device and Forscan comes up with:
Service Procedures:
ACM Module Calibration
ACM Module Reset
Config and Programming
ACM Module configuration (AS BUILT format)
ACM Module configuration