Q: HELP!: Mac Pro 2013 - No Audio Input Devices Found

I've been having intermittent audio input problems for a couple of months, but today it came to a head, with NO input source being detected (by core audio, I assume).

All my devices are showing up in System Information, but nothing in the Audio Input or Output.

Previously, the majority of the problems had been with USB Audio Devices, with Audio turning into extreme static and echo for about 15 minutes.  After that amount of time, the audio would clear up and be great until I shut down the audio app and restarted it.  Then I would have to wait for another 15 minutes.  This occurred in ALL apps: Garageband 10, Logic Pro X, Amadeus, and even Quicktime Pro 7.

However, starting yesterday, I started having the same problem over Firewire, where after a couple of minutes, the audio would turn into loud static and echo, and the volume of the recording would increase from -3dB and over +20 dB.  Now, as of a couple of hours ago, System prefs can not see any audio inputs or outputs.

In trouble shooting this problem. I have restarted each app several times, restarted the Mac several times, reset the SMC and NVRAM.  Still no Joy!

Would anyone have any further suggestions on how to trouble shoot this problem?

Any help or advice would be greatly appreciated.

TIA