Please help unsuck my ram

[Woosatch]

For starters, this is my first post so don't be too critical if I use the wrong terminology.  So here we go.....I have a 2016 Ram 2500 with the 8.4/RA3 HU and use the AP4-CH41 or can-bus integration piece, between the HU and factory amplifier.  Overall, it did exactly what I wanted by allowing me to retain the factory HU and controls except for surround and speed volume.   I will say that it sends a very flat or clean signal up to about 2.5v, and in my case, to a Audiocontrol DM810 DSP which is used as the main tuning device.  The PAC piece has a fairly weak output signal (<.6v) until the HU reaches two thirds volume or (lvl 24).  The output voltage increases almost exponentially every level higher to a max of 5.2v at lvl 36.  Depending on the source, the output signal from the PAC piece at 40/70/1000hz is clean on a scope to lvl 30 (2.1v) and sometimes lvl 32 (2.5v).

I just call lvl 30 my max volume for setting gains.  The 4/5v dip switch had little effect (<.25v) on my measurements.  To put it mildly, trying to properly set input and output gains with the provided signal on the DM810 was the single most frustrating experience I can remember because it was low and lacked consistency.  In my case, this caused unwanted noise floor (gain hiss) or dirty output signals from the dsp.

**Side Note** I have some strong opinions about the DM810 after going through this process but I will save those for another thread.

Determining or providing the proper input sensitivity setting (high/low), and gain adjustment on my amps with "X" input / "X" output gain from my dsp at "X" volume on my HU was comparable to Chinese arithmetic.  I used the minimum volume option included in the PAC software (ampPRO) to keep the voltage range under a certain level but that created more noise floor issues while trying to efficiently drive my speakers at lower volume levels. 

Keeping my HU volume constant and using the dsp as a master volume control would solve this problem but a second gain/bass knob would need to be installed for the sub or switch memory settings on the DM810. The second knob, either to the amp or PAC piece, wouldn't be the end of the world but having a call come through while listening at a high level would make you want to jump out of the truck.  I enjoy having my handsfree, nav, and chimes at their respective levels separate from my music.  Hope this helps and if anyone has any questions I'll try to answer them if possible.