Audio crackle on USB DAC

Issues & Assistance
1

A Schiit Modi (alsa_output.usb-Schiit_Audio_Schiit_Modi_3-00.iec958-stereo), plays audio crackles when audio is playing. This does not occur on Linux Mint.

Per ArchWiki and various posts, I’ve tried:

  • Every combination of PipeWire default.clock.rate and default.min-quantum (.conf in ~/.config/pipewire/pipewire.conf.d)
  • Every combination of WirePlumber audio.format, audio.rate, and api.alsa.period-size (.conf in ~/.config/wireplumber/wireplumber.conf.d)
  • Every quantum set via CLI: pw-metadata -n settings 0 clock.force-quantum n
  • PipeControl: Adjusting sizes of buffers
  • Outputs: digital, Pro Audio, analog
  • Kernels: cachyos, cachyos-bmq kernel, cachyos-bore, cachyos-rt-bore (+/- kernel flags preempt=full and threadirqs), cachyos-lts
  • performance mode: echo -n governor | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
  • sudo nvidia-smi -pm=1 with every combination of sudo nvidia-smi --lock-memory-clocks=n,n and sudo systemctl start --now pci-latency

Crackling is intermittent and apparently unrelated to the source program, format, and rate; CPU load; and storage r/w activity.

2

Ideas:
Switch to LTS kernel

  1. How to install another kernel on CachyOS
    Managing Linux Kernels & Sched-ext framework with the CachyOS Kernel Manager | CachyOS
  2. How to make your CachyOS install boot into that kernel instead of the default one

If using GRUB bootloader:
Setting the top-level menu entry - GRUB - ArchWiki

Or install pipecontrol and force a larger buffer size?
paru -S pipecontrol

Or try what this user said a while ago which I think is pretty expert way of solving it:

3

Thanks for the ideas, but, as mentioned, none helps or even seems to have any effect.

4

Other ideas that have worked for others, but I haven’t tried, include:

  • Changing PCIe from Gen4 to Gen3 in the BIOS
  • Rerouting cables in the chassis
  • Using a USB expansion card

Plugging the computer and audio equipment into an AC outlet filter also didn’t help this issue.

One thing I hadn’t mentioned is swapping the USB cable. (IIRC, this is the first thing I tried and it didn’t help, but that was months ago and I’ve searched and tried much since.) Regardless, I tried swapping the USB cable again, and voila! The problem seems sovled!

FWIW, the replacement cable is thicker than the old, stock cable, which had been working flawlessly for years with other computers and operating systems.

Therefore, even if CachyOS contributes to this issue, my solution is not CachyOS-specific.

5

Since I didn’t see anyone mention my solution, I’ll add it.

Had a Schiit Modi 3 that had a random crackle. Cable wasn’t the issue, but the USB port was. USB 2 should be enough, but the crackle went away completely when I swapped the cable from one of the USB 2 ports on my motherboard to one of the USB 3 ports on my motherboard.