I didn't realize that the volume increase option within Kernel Auditor was was only for headphones. Its been awhile since I have used any of the deeper options.
I am not sure why you are having a volume issue with AICP 12.1 for me it was fine. Perhaps there a way to increase volume with build prop? Paranoid is a great Rom. The only thing I don't like is it can be a little too loud and its bass frequencies are cut too far in.
Maybe try installing Arise:
https://forum.xda-developers.com/android/software/r-s-e-sound-systems-auditory-research-t3379709 I use it it has practically every sound plugin combined into one Aroma option.
By the way Viper4 will definite increase the volume, and you can set up profiles for the speaker, BT, and USB audio individually If music audio is too compressed just turn the option compression off, and use EQ rolloffs at 100 mhz and 10000 khz.