Hi there, I've got an issue relating to my O2dac/amp (device) which was purchased sometime in 2015.

Background:
The device is used with a Sennheiser HD 650/ JBL LSR 305 and connected to my laptop via usb. I recently changed the setup and replaced the laptop with a brand new self built desktop pc (5 days old). I plugged the device to my laptop and realised that the speakers were emitting a crackling/ buzzing sound. The headphone port was fine without any buzzing/ distortion. Unfortunately as of today, even the headphone port had a buzzing/ distortion to it. I tried both my IEM and HD 650 and both were able to replicate the noise. Distortion/ noise on the speakers got worse.

The speakers are connected on a separate power strip to the PSU (power supply unit), but both power strips are plugged in to the wall next to each other. I moved the PSU connection to another wall outlet further, but the noise remains.
I have tried plugging the device via usb to all the usb ports on my pc and there's no change in the noise.

The noise gets worse when I launch a game, the audio gets crackly and distorted and louder.

I have plugged the speakers to my phone and played off it, no issues.

Note: when the speakers are just plugged in, powered on, not connected to anything its noisefloor is slightly audible (which was not an issue when I was using laptop). Am connected to internet via LAN, have tried onboard WiFi with antenna and LAN, both have the noise.
Question:
What is causing the interference? PSU/ GPU? Bad shielding? Power loop etc?
Could it be the device failing?
Is the desktop PC introducing some form of electrical disturbance which would warrant a power conditioner?
CPU: AMD Ryzen 5 3600
Motherboard: Gigabyte x570 Aorus Pro WiFi
Ram: Corsair Dominator Platinum 32GB
SSD/HDD: Intel 760p nvme (OS)/ Adata SX8200 Pro
GPU: Gigabyte 2070S Gaming OC White
PSU: Fractal Design Ion+ 660w Plat
Chassis: NZXT H510 Elite
OS: W10 Pro 1903