Build 334: AAC 24bit conversion - audio artefacts [Resolved B339]

Build: 334
Endpoint: Squeezebox Transporter

Symptom: I’ve been listening to some of TIDAL’s AAC output which goes through Roon’s new 24bit conversion.

There are some odd audio playback artefacts - at higher peak levels within the track it sounds like a sort of clipping is introduced - a highish frequency ‘crispy’, ‘speckly’ sound overlaying the track.

FLAC is unaffected. I’ve tried somelocal mp3 as well and can’t detect any problems there.

Hi Mark, have you tried applying some headroom in DSP?

Good shout, I’ll try it for the sake of troubleshooting.

OK, just tried through the headphones on my PC. Here are the observations:

  1. The tracks are indeed clipping as show by the red indicator
  2. Switching on volume normalisation gets rid of the red clipping indicator.
  3. The audible artefacts don’t go away!

If anyone wants a sample track to try on TIDAL then

It doesn’t seem to be a Squeezebox conversion thing, but it still might be a Linux thing.

Sorry Mark, unable to find that track/album… Must be a regional thing?

Nevermind, i did reproduce the issue with a favorite of mine:

Just Headroom activated (0db) and clipping indicator!
Ticks and pops on the playback, particularly in peak moments…
Think @support need to have a look.

Great band.

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I have a Bluesound Vault which can play back the selected track from Tidal without Roon involvement. The Vault does not produce any audible artefacts when playing from Tidal, but when i RAAT the same song to it as any endpoint it sounds distorted (and worse than the Bluesounds own streaming).

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Indeed. I didn’t have any issues with Roon’s conversion prior to 333/334.

@anon55914447 and @Mikael_Ollars ---- Thank you both for the feedback and sharing this observation you have made while listening to the mentioned albums/tracks! The insight is greatly appreciated!

Moving froward, I had shared your observations with our tech team and asked them to bang on this a bit to see if we could reproduce this this behavior in our QA labs. Our techs tried to reproduce with the following setups (playing the same content) and unfortunately were unable to do so.

  • SonicTransporter5 (Core) – Squeezebox v3 (endpoint)
  • ST – WIn10 System Output.

In light of this, the team has asked for the following:

  • Please provide screenshots highlighting all the playback/zone settings being used in Roon when you notice these audio artifacts.

  • Mark, you mentioned in your second post that you observed this while listening through the headphones on your PC. Can you please provide some further insight into this configuration so I can add it to my report?


Hi @eric, this is what i see on the signal path:

The USBridge is feeding my DAC, an Audiobyte Black Dragon. My Roon server is on a Qnap TS-470 Pro with an i5 processor, 16Gb RAM, 60Gb SSD for Roon DB and 3*6Tb WD Red spinning disks for storage. The network is wired except for a wireless bridge between the NAS and switch (unmanaged Gb HP Procurve). (allows me to play local DSD256 with absolutely no issues)

Adding my DSP settings also:

Coincidentally, I have the same album as Mikael in the same format

Here I left the headroom adjustment and volume levelling on as per Mikael’s original suggestion, but it doesn’t matter - the artefacts are present either way. I usually have DSP off completely (my usual squeezebox config).

The common bit with Mikael is the QNAP core.

@Mikael_Ollars try the track I posted. The effect is MUCH more pronounced.

This one is also particularly easy to hear (Tidal again).

I found it at last!
And yes, there’s a lot of ‘knittering’ sounds in the loud parts! (only when playing in Roon, with my Vault directly from Tidal it is loud and dirty but nowhere near the distorsions via RAAT)

@anon55914447 and @Mikael_Ollars ---- Thank you both for the follow-ups! Having this additional feedback is very appreciated!

Confirming that I have updated my report with this information and have since passed it back over to our techs fro review/further testing. @anon55914447 were you able to give any thought to my question above regarding the mentioned PC? Would love to get that into my report as the team asked for that information specifically. Thanks!

“Mark, you mentioned in your second post that you observed this while listening through the headphones on your PC. Can you please provide some further insight into this configuration so I can add it to my report?”


Sorry what configuration do you need?

Signal path is as shown in the screenshot.

PC is Win 10 Build 17134
Headphones are Sennheiser PC363D via their G4ME1 integral USB DAC


since Update to build 333 (now 334) i have heavy glitches in every TIDAL stream. Normal files from harddisk works without any problems and before the update was done TIDAL hasn´t any issues. My system are Roon Core on Synology NAS, Roon Endpoint is a Metrum Ambre.


Hi @Soeren_Schulze ----- Thank you for the report and sharing this observation you have made with us. The insight is greatly appreciated!

Moving forward, I wanted to first touch base and see if any progress was made here? Did you get around to rebooting your various devices as mentioned in @andybob’s post above (i.e core machine, endpoint, router, etc)? Always a good first step in my most humble opinion.


I made a reboot of Router/Nas/Endpoint and a reinstall of Roon Core on the Synology NAS but without success. The clitches are in every playing at the same position of the TIDAL files but not every TIDAL file has this problem, maybe 70% are problematic. In my view that is not a bandwidth problem, the rate is constant and the TIDAL files are preloaded in 2-3 seconds. A other difference are between the local stored files and TIDAL is the format AAC 44,1 Khz 24Bit vs. FLAC, WAV, MP3 etc. I have also tested a other endpoint (MacOS Roon) with the same clitches, TIDAL App on Ipad and under Windows 10 runs perfect.There must be a problem of routing TIDAL in the Roon Core on the QNAP NAS!?

Hi Eric,

I’m hearing the same crackling distortion on track #2 (Down to Rest) at about 1:30 mark, in Mark’s example above.

Using my ROCK NUC thought IQaudIO DAC to my speakers.

I also had Headroom management on (only) with -3 adjustment to avoid the clipping indicator.

Cheers, Greg

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