After multi-diagnostics and cleaning finally uninstalled the newer drivers completely and prevented windows from updating the device ID drivers after it installed generic drivers.
Then I went back to Dell site and installed the older device specific drivers. Noticed an improvement but not a complete solution. Eventually upgraded just the HDMI driver through Driver Booster with very little difference. Still better then originally.
Thought there might be some loose Port connections as there is some wear on the unit and at least one tricky USB Port. While the Display Port is slightly loose I don't think it's the issue.
Swapped the HDMI cable today and plugged it into a different Port on the AV unit and seems good or slightly better after a single cutout. Thinking of getting a newer HDMI cable with better specs just to try.
I think I'm down to either the HDMI or connections, a wear or abuse issue on the unit, or some driver conflict. Maybe I'm just too picky but as this is essentially my Home Theater Streaming Box I would like to have the audio work properly.
Still open to any suggestions.