HELP NEEDED with USB Audio Interface and noise issue

I've been trying to fix this issue for weeks now. Ultimately, this is the only issue with my Hackintosh build.

I am using a 24-bit, 192khz USB powered audio interface and it is producing a subtle bit-crushing noise when there is no audio or the audio coming through is very low.

The interface does not produce the issue when plugged into my iMac or MacBook Pro - only happens on my Hackintosh.

Here is what I have tried so far:

• I am using balanced cables to connect my speakers.
• I have tried 3 different USB cables - all have the same issue.
• I have tried using different cables to connect my speakers.
• The headphone output does not appear to create the same noise (when listening via headphones), but if I connect my speaker to the headphone jack - it produces the noise.
• I have ensured that my output is set to use the 24bit/192khz option in the Apple Midi utility.
• I have created my own SSDT (via RehabMan's awesome guide) and have ensured that only my active USB ports are properly displaying in the IOReg
• I have verified that the USB power on my interface is drawing the same mA as my MacBook Pro and iMac (500mA)
• The data rate for my interface via USB is displaying as "up to 480mb" (same as my iMac and Mackbook Pro)
• I have used both HDMI and DP cables to connect my monitor.

The issue seems to be influenced by what is drawn on the screen - some activities will introduce more noise (moving windows, opening apps etc.)

My Hackintosh has been setup using the Vanilla install and I have the following kexts for my setup:

AppleALC

Lilu

SMCProcessor

SMCSuperIO

USBInjectAll

VirtualSMC

WhateverGreen

I am using the iMac18,3 for SMBIOS (changed from iMacPro) and no difference. If there is anyone out there who can offer some help I would greatly appreciate it.. so frustrated with this...