audio distortion

Sorry, for stating the obvious, but have you tried any/all of the following:

1. Plugging in a known good pair of stereo headphones into the mini's audio port?
2. Tried both the analog and optical-digital outputs from this port? That is, used the appropriate audio cables and destinations, tried both analog and digital output to see if there was any difference?
3. Tried alternative audio sources, i.e., iTunes, Spotify, audio CD, etc.?

Sorry, I just saw I had a reply.

1. Yes I have tried multiple output devices that I know work otherwise.

2. I don't have a way of testing the optical output. We are attempting to run an 1/8" to XLR directly into a mixer. Currently having to run an 1/8" to 1/4" into a DI to kill line noise, then to an XLR into the mixer.

3. I have tried all of the sources. The issue seems to be something internal. For some reason when it plays any audio signal it is boosting that signal to a peaking level even though the volume control is literally almost at 0. It is at 0.09 to be exact and the signal it is sending in still distorted a slight bit due to volume output.

I am not sure I am explaining it correctly, but I will try this way too. Volume output is able to be controlled by all volume controls in all apps. The issue seems to be the internal volume the Mac Mini is attempting to play ALL audio files is so hot it is peaking. So when I attempt to play any audio track or file, the master volume control has to be turned almost to 0 for it not to peak and distort.

Thanks for the additional information and explanation. It was helpful in understanding the issue you are having with your mini. Unfortunately, I don't have anything else to offer you for potential solutions. It just may be that the issue is a faulty system board and/or audio port.