2020 Intel iMac: Low input from external microphones

Hey all, a friend and I record videos through OBS. The issue we are having is with any external microphone he uses with his 2020 Intel iMac (has the newest Tahoe update) has what seems to be a weak signal. We have tried a couple USB mic's and now using an XLR mic through an audio mixer but all with the same issue. He has the system Input volume at 100%, 100% in the Audio MIDI settings and his audio mixer is also maxed out. His levels average around -30 to -25db which doesn't make sense to me because all inputs are raised to the max. Obviously, the issue with all his gains maxed out, is it adds so much unwanted noise when I try to raise it in editing. He is only 6-10inches from the mic when speaking as well. I own an M1 Mac Mini which I tested the same Mic he's using on and had no issues and was able to set my input to about 40% sounding perfect. We eliminated OBS as the issue because his audio sounds the same in Discord and other programs as well. I've been looking for a fix for months now and nobody seems to have any answers or suggestions. Any help would be greatly appreciated.