GPU Noise issues in SMSL SU-8S DAC

Having issues with GPU noise on a SU-8S connected via USB. It is externally powered. Motherboard on the PC is the Asus ROG Strix B550-F Gaming. GPU is the EVGA 3080 Ti FTW ULTRA.

Audio Chain

[Source - PC] -(USB Type B Cable)-> [DAC - SMSL SU-8S] -(RCA Cable)-> [Power Amp - Parasound zAmp v. 3] -(Speaker Cables)-> [Speakers - JBL 530 Speakers]


  • I am getting a lot of buzzing noise when gaming occurs. I believe increased GPU loads are the source of the noise. There is no noise when there are no games running.
  • Noise seems to occur between the DAC and the PC Source via USB.
  • Even when the DAC is turned off, the noise seems to make it to the speakers through the power amp from the PC Source. Unplugging the USB cable will stop the noise as does unplugging the RCA or turning off the power amp.

Attempted Fixes

  • I have tried to fix any ground loops by doing various combinations between two outlets. Having the audio equipment and the PC on separate outlets or sharing one outlet via surge protectors. Issue persists.
  • I have tried various USB ports from 2.0, 3.0, and 3.1 ports on the rear of the motherboard. Issue persists.
  • I have tried using the ifi Defender+ to lift the ground of the usb port the DAC is using. Issue persists.
  • I have tried multiple RCA Cables to see if this fixes it. Issue persists.

Anyone have any idea what the issue is or what I should try next? It seems to be coming from the source. I’d like to get this working via USB if possible, but my last resort is a Toslink as that should prevent the noise at the source. Would a USB Type B cable with ferrite chokes help?

Thank you!


Another option, if the slot is not occupied and there is room, would be to connect a USB card via Pcie express.
It does not have to be the most expensive one.
This could possibly help.

Otherwise try another dac if you have one handy or borrow one to see if it gets the same or better.

I don’t have another DAC handy, but I have a internal soundcard that the DAC replaced. The internal soundcard had the issue and I am disappointed to say that the issue is the same on the external DAC. I may look into a USB card, but would rather not clutter my PCI-e slots if possible. I may just be forced to use Toslink unless someone else has a solution.

Idk if you’re not trying to spend that much, but could try a cheapie DDC like the Douk U2 pro. It’ll separate your power from your signal completely as long as you’re not powering it from your PC.

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Yeah, I believe the ifi Defender+ does that where it cuts the usb power lines and just sends signal. However, it introduced a high pitched noise in place of the buzzing when I tried that.

The DDC you could send signal out as coax to your DAC though and probably not only eliminate the noise, but also improve the quality a fair amount.

Before spending a bunch of money I’d try an RCA ground loop oscillator between dac and amp:

My system has a ground loop and a similar gizmo cleans it up nicely. And if it doesn’t work, it as a $10 shot.

some things I found worked when I could hear noises especially when moving my mouse through a usb connected dac
topping usb audio isolator (usb to usb) $70ish
douk audio U2 (usb to toslink converter) $40ish for the cheapest
using a soundcard with toslink out $40ish for cheaper ones

i had usb noise. these fixed it.

You could try getting an external USB-C dock since your MOBO supports it and connecting the DAC via a USB port on that. I’ve had less issues with electrical/GPU whine etc on USB -C devices in the past. Some docks also allow for external power ins so you can decouple from the main PC power entirely while still transmitting data.

Update: So despite my DAC not being USB powered, using the ifi Defender+ with power connected actually cut the noise down a lot. However, I ended up trying toslink and found 0 noise at all bleeding through since it is an optical connection. So I ended up sticking with Toslink.

I could’ve lived with the ifi Defender+ solution, but the toslink cable solution was way cheaper and feels even cleaner than the ifi Defender+. So I ended up returning the ifi Defender+.