Halp~ It's noise, it's always noise. (PC/Console Mixer setup)

Equipment: ROLLS MX44 Pro Four Channel Portable Stereo Mixer, JDS OL DAC, BESIGN Ground Loop Noise Isolator, PS5, Nintendo Switch, PC, Vanatoo 2.0 speakers. All devices have their own power support except the noise isolator obviously. All of these are connected via 3.5mm stereo cable with the exception of the one USB Digital Out from the PS5.


An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.



Experience preface -
I have about 20 years of experience with computers, building them and mostly plug and play aspects of audio.
I understand the difference between digital and analog input/output, I know next to nothing about frequency and wavelength differences between the two.
This is my first attempt at a mildly complex sound system. Without oversharing too much I'm a contractor who likes to keep my setup simple and compact so that I can fit it all nicely into a small car when it's time to leave, so I've created a PC/Console setup that uses dual monitors and video output to both with audio being controlled by the mixer so that I can hear two sources at a time.
First problem that helped me learn a bit about digital out was that the PS5 has no analog out, this was never a problem before since I used HDMI on TV's, but unlike the PS4 there is no optical out either, which leaves us with USB or HDMI out only. It is actually reasonable as most people will only be using a switcher at most for console use. After getting the DAC and in my inexperience, I thought, "It's all analog out now everything will work great", well here we are.
Posting an image of my layout from a top down view. I'm not including the video side since it's basically removed from the scenario as I do not have a $5000 AV Mixer.

The Problem -
I'm getting noise, from what I understand this is the great hunt of audio tweaking and there isn't always a simple or cheap solution.

Through expiramentation I've found a few things:
* It's not just unclean noise, it is a steady hum.
* I have swapped the 3.5mm for L/R cables and the noise remains the same.
* The problem seems to stem from the output of the PS5 in combination with the mixer.
* Adding Ferrite/Iron rings to eliminate noise has done virtually nothing with any of the cables, I just left the one BESIGN because I didn't want to unplug it and it hasn't changed anything.
* The mixer channels show correlating noise volume depending on the volume of the PS5 input in Ch1 and output of Ch
* I have put headphones into the 3.5mm output of the mixer to see if the noise was with my speakers, the noise remains consistant.

I'm happy to be wrong about any of these points but I will explain my process of elimination:
1. The noise is gone if the PS5 analog input is removed from the mixer.
2. Different channels seem to correlate with the noise volume, aka when I have the PS5 plugged into ch1 and the nintendo switch into ch.3 the noise is there but as I adjust the volume dials for each there seems to be a sweet spot where the noise either cancels out or is reduced to almost nothing (to human ears).
3. The same happens with PS5 in ch1 and the PC in ch4
4. The effect of having all 3 devices plugged in at a time compounds the issue, the volume doesn't increase but finding the sweet spot seems to be narrower in changing the volumes of all 3 channels.

With tweaking I've found a temporary harmony that I can adjust the volume on the monitors and be happy but obviously I would like for my mixer to be able to function as volume control for all so I'm not reaching around and adjusting monitors and messing with PC output in windows.
My main thought is the weakest link is probably the piece of equipment is spent the least on and am relying the most on, the mixer. Would getting a new more expensive mixer with actual frequency adjustments possibly solve this? would a different DAC help? any advice?
 
I believe You are using RCA cables Right ?
A simple test.
Leave the mixer on and disconnect all the input cables and let them sit on the floor /carpet.
Is the hum still there ? Rule out the cables.
One time I was getting hum on my Sony AV amp and found out one of the RCA cables I was using was cheaply made. Confirmed by scavenging it. Normally they hum when finger touched.
 
The ground loop analysis requires knowing all connections to class I isolation devices (= with the protection earth wire) (including TV, monitor, etc.)

The ground loop isolator seems to fail sometimes https://www.amazon.com/gp/customer-...f=cm_cr_arp_d_rvw_ttl?ie=UTF8&ASIN=B06XQYN77L - is your piece working correctly?

If the isolator is working correctly, I do not see how attaching the wire going from the isolator to the mixer could create hum. Are you sure your chart is complete and correct?