Crackling throughout track

Core Machine (Operating system/System info/Roon build number)

MacBoookAir6,2 (i7/1.7GHz/8GB/SSD) running macOS Mojave 10.14.6 and Roon Version 1.7 (build 511)

Network Details (Including networking gear model/manufacturer and if on WiFi/Ethernet)

Laptop is connected via ethernet to Airport Extreme.

Audio Devices (Specify what device you’re using and its connection type - USB/HDMI/etc.)

Apogee Duet Fireware -> Thunderbolt dongle -> Back of LG monitor --Thunderbolt–> Laptop

Description Of Issue

Constant background crackling noise on songs. Duet is in exclusive mode. Have tried with headroom and upsamping both on and off without any change. When I play the same music in Qobuz directly or over in iTunes (Apple Music) or Spotify no such crackling is present.

Hello @Christopher_Hesh,

It would appear that your DAC is struggling with the CoreAudio Exclusive Mode setting. Roon uses the built macOS API to communicate with the DAC in exclusive mode, so I’m not sure what could be causing this issue to occur.

It should be noted that none of the other applications you’ve tested with support CoreAudio exclusive mode, including Qobuz (Qobuz changes the sample rate of the DAC but it is not “Exclusive Mode”).

I would first try playing around with the integer mode and buffer settings in the Device Setup screen in Roon.


Tried “Enable Integer Mode” as well as “Use Maximum Buffer Size” and “Use Power-of-2-Buffer Sizes” without any luck.

I changed the max bit rate per sample from 32 to 24 given that the Apogee Firewire is 24bit/96kHz. I turned everything off in the DSP so the signal path is:

Source (24bit/96kHz) -> This Mac -> Duet (Exclusive Mode)

Crackling still present.

I only have a few days left on my trial before I have to make a decision about purchasing. Are there any other possible solutions to my issue?

Edit: I’ve taken the Duet off of Exclusive Mode and the crackling sound is still present.

I am also experiencing crackling distortion. My setup is similar - iMac late 2015 with macOS Catalina running Roon 1.7 build 667. My output is thunderbolt to firewire converter into an Apogee Duet Firewire.

I hear distortion:

  • on all high resolution MQA files streaming from Tidal
  • on some local 16/44.1 FLAC files

I don’t hear distortion:

  • when streaming 16/44.1 Tidal files in Roon
  • when playing MQA files in the Tidal app
  • when streaming Tidal MQA files in Audirvana
  • on MQA files when the Built-In Output is selected on the iMac and playing through the internal speakers

I tried changing various audio settings in Roon but it didn’t change the distortion. I am guessing the issue is between Roon and the Apogee Duet because I am not able to reproduce the distortion in other apps. Is Roon not compatible with Apogee Duet Firewire? Thanks!

Hello @Michael_Corcoran,

I did some research regarding the Apogee Duet Firewire and crackling on macOS and found many similar reports like this:

I’d recommend trying the following:

A) Playing around with the CoreAudio buffer settings in Device Setup. Try toggling the “Maximum Buffer Size” and the “Power of Two Buffer Size” independently to see if you’re able to get things working.

B) Use Roon’s DSP Engine Sample Rate Conversion to resample everything to a single sample rate. This could reduce the chance that issues occur with resyncing + changing buffer sizes.


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