Weak transmission from both radio..

I have a GTN 650 and GTR200 working through a PMA450 audio panel. Indvidual bent whip antennas on belly.
When I transmit from front cockpit on either radio, air or ground, transmission is weak and muffled. Have tried 3 headsets, all the same.
From the rear cockpit all is normal.
My reasoning is since it all works from the back as advertised that I must have an issue with the front mic jack or another ground issue up front.
PMA doesn?t have individual output controls. Works great frm rear cockpit.
I?m going to pull the audio panel and check the mic jack barrells for good grounding. If that?s good, what?s next.

Where else should I check?

Does the intercom work okay from the front seat? If no, pull the input pins and swap front and back seat inputs. (Back pins to front inputs). If the rear seat now has the issue, the problem is in the audio panel. If the problem stays with the front, look hard at the wiring.

Intercom works perfect from the front seat,

Close this one out for now.

Well, I took out the forward mic jack and put in new isolation washers and also removed a heavy duty mic muff from my headset. One of them fixed it. I?m guessing the mike jack was groundng out enough to interfere with the transmission. Gremlins....

Yet it always worked with the intercom. Strange gremlin indeed.