Thumping noise in headphones

[viktri]

Please let me know if I'm posting this in the wrong place.

I have the Beyer DT770 250ohm headphones (I actually bought a second new pair because I thought the problem was with my headphones so I have 2 pairs of the DT770 250ohm) and when I use them with a computer DAC dongle like the Filo KA3 or the Dragonfly Colbalt plugged into the computer via USB C or USB 2 or USB 3 there is a constant thumping or static sound. If I plug it into the computer there will not be any sound. However, once I start music or a video that has audio, the thumping/static noise starts. Turning off the video/audio does not stop the thumping/static sounds.

If I plug in the headphones into the computer without using a dongle and directly into the computer's headphone jack, there is no thumping/static sound.

I've tried different cables but I don't know how to get rid of the sound.

Wondering if anyone can help me here. Everything is plugged into the same power bar which is plugged into the wall. This also occurs on my laptop. This occurs with 2 different dongles. Was was wondering if someone could point me in the correct direction.

I purchased these USB dongles because I thought they would have a small footprint on my PC. Would this issue be eliminated if I purchased a larger DAC/AMP?

 

[staticV3]

Does it happen even if your laptop is running on battery?

 

[viktri]

Does it happen even if your laptop is running on battery?

I never ran the big laptop on battery because it's a gaming laptop (doesn't last long) but USB dongle DACs (filo ka3 and dragonfly cobalt) works fine with my Macbook Air M1 on battery.

I was recommended iFi Audio iDefender but the cost is approximately $100 - I think I could purchase an external DAC for a little more (I assume they're better than the USB dongles, might be wrong there).

 

[staticV3]

If it happens on multiple laptops and PCs, but only when they're connected to mains, then you're closer to finding the culprit.
Next I'd try plugging the laptop/PC into different outlets around the house.

 

[viktri]

If it happens on multiple laptops and PCs, but only when they're connected to mains, then you're closer to finding the culprit.
Next I'd try plugging the laptop/PC into different outlets around the house.

I purchased the iFi defender but it didn't solve the issue unfortunately. It also doesn't allow me to power my DAC when plugged into USB for some reason.

If I plug the headphones into the headphone jack of my PC, there's no thumping noise. If I plug it via USB (C or normal) the thumping noise persists even with the iFi defender.