Pro-Ject Pre Box S2 Digital intermittently drops a channel when playing from roon

Roon Core Machine

Roon 1.8 (Build 943) in docker, on Unraid (Version: 6.9.2), AMD Ryzen 9 3900X 12-Core @ 3800 MHz, 32Gb DDR4

Networking Gear & Setup Details

Unraid box → cat6 → 1Gbps ethernet Netgear switch → cat6 ->streamer

Connected Audio Devices

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Number of Tracks in Library


Description of Issue

The Pro-Ject Pre Box S2 Digital intermittently drops the right channel when playing from Roon. The image above shows the component chain for 5 different tests performed. The common factor seems to be that only when the music source is Roon does the error manifest. I’m using the default values Roon offers for the DAC.

Hello @Jonathan_Crawford1 and welcome to the forum.

Please check your signal path in Roon. If you have questions interpreting your signal path, please post a screenshot thereof here.
The various channels of digital audio streams are interwoven (1 stream, 1 connection/cable). There is no way a channel drops without according mathematical instructions executed by some calculator (processor/CPU/DSP). If your signal path does not show respective operations being executed by Roon then check your devices down your chain. The source for similar issues in the past was often located on the DAC or analog side of a users chain.

Disclaimer: From another users trying to help.

Hi @BlackJack, thanks for the response. When you say “check”, check for what?

If you look at the 5 different tests I have performed I have swapped out every component in the delivery chain except the “Media Source” (Tidal) and the speakers not shown of this diagram.

Looking right to left - the first component swapped was the amp - Test 1 was using an Arcam AVR 550 and then a IOTAVX AVXP1 power amp for Test 2. In both instances the right hand channel intermittently dropped, although there is a feint “popping” noise that follows the tempo of the music heard from the right hand channel, its not totally dead.

Test 3 changes the the streamer software, so changing the software implementing the Roon endoint. Initially I was using Gentoo Player, then swapped it out for Ropieeee (which I use in 3 other zones). Again the playback error was heard in both tests.

Test 4 changes the streamer hardware and replaces the Allo USbridge Signature with a Raspberry Pi 4 running Ropieeee, again the playback error was present

Test 5 changes the streamer to a Galaxy Note 10 5g phone, using the USB Audio Player PRO software (to bypass Android’s sound reproduction quirks). In this instance, the same Tidal playlist is streamed directly to the streamer i.e. not via Roon. This is the only scenario under which the playback is as it should be.

In my mind this proves there is no issue with the DAC and all other downstream components, as they have be proven to work flawlessly when fed audio from the phone. This issue only manifests when Roon is in delivery chain. I’m hoping this is just a software config issue, hence posting here.

I’ll run through the first 4 setup’s again and take screenshoot of the signal path for each. Obviously I can’t get a signal path from the last non-Roon setup. I can however confirm MQA indicator lights on the DAC under this setup.

I’ll go get busy, but I not sure comparing signal paths of the 4 identically faulting setups is going to help me with debugging this. Hopefully it may give others the info to be able to help me.

Thanks for your assistance

Audio processing settings.

If all other devices work as expected, then the channel separation happens in the DAC and stays discrete afterwards. In my mind there is nothing to proof here because what you hear is already proof enough. As of the “Why?”, this is another question and why I asked about the signal path. You can also try and reduce the volume in Roon (use volume leveling, use headroom in the DSP section) - maybe you’re just “overdriving” your DAC when you use Roon. I suggest you also contact Pro-Ject support to discuss your issue with them too as all what you wrote so far points at your DAC as source of the issue.

Thanks again for the response.

I just fired up the system to gather some signal screen shoots. The config was as per test 4 (Tidal → Roon → RPi4/Ropieeeee → Pro-ject → IOTA) and to 15-20 mins I could not reproduce the fault

I :heart: intermittent faults.

Too many outdoor jobs I need to be getting on with for now. I’ll try again later


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