Default [Q] Low microphone volume

So after about an hour and a half of searching XDA and Google I have yet to find a resolution that doesn't involve me opening up my phone and cutting the rubber around my microphone. Allow me to explain.

Since I can remember - I got my S4 in December of last year - I've had problems with people hearing me, low record volumes and so on. I rooted and modded my phone almost immediately after receiving it and never really had the chance to test on stock TW, but this problem has persisted at *least* since I switched to KitKat about 2 months before it was pushed OTA via Carbon and Pac ROM. I have made it a regular habit of removing any DSP/preinstalled audio software and using Viper4A, but I was hoping to get some sort of lead before I flashed again, revert to stock TW, or took apart my phone.

This problem was reported fairly commonly with the SII and the Nexus 4, but the methods I have tried to solve the situation (*#*#197328640#*#*; Trickster Mod, mixer_paths.xml does not exist...) have yielded no results.

I'm posting because I haven't seen any issues of this nature reported for the S4. While I cannot deny the mic port could be partially blocked, I tend to obsess over taking care of my things. One thing I have noticed is the presence of two microphones... one on the top of the device (for sound cancellation?) and one at the bottom. When using a sound recorder, the volume recorded from the top microphone was at least 5-7dB louder than that of the one at the base.

Could anyone point me in the right direction? Kernel tweaks? File modification I'm missing? Anything?

EDIT: Well, I found this tidbit of information regarding the two microphones:
There are two mics on the S4, the one on top of the phone is used for speaker and voice commands and the bottom of phone mic is used for phone calls.
How I managed to own the S4 for 6 months and not know this (which is also the case for the SII and SIII) is beyond me and answers a few questions I had, but I'm still at a loss as to how to adjust the recording volumes. I tested with Zello's outbound transmit volume and there's a dramatic difference - it seems to affect both microphone's sensitivities - but how to adjust this on a system-wide level still eludes me.
Spiricore's Super Safe Root-To-ROM Guide
for Sprint's Samsung Galaxy S4 (SPH-L720/jfltespr)
Baseband: NAE Recovery: Philz 6.43.8
ROM: Carbon ROM Nightlies
GApps: Paranoid Android 0-Day
Mods: Xposed Lux Viper4AndroidFX Mother of All Ad Blocking

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