Hi,
I’ve just started my Roon subscription and I’m using it on my Windows 11 PC. For audio output, I’m using a Raspberry Pi running Moode, connected to a MOTU M4 DAC.
I’ve installed RoonBridge on the Raspberry Pi, but I’m running into two issues:
DSD playback: I don’t see an option for native DSD in Roon. However, when using Moode’s MPD player, native DSD works fine with this DAC.
Channel output issue: On the MOTU M4’s display, I can see that music is playing on channels 1+2 (as expected), but there is also a constant full-level signal on channels 3+4, even though those channels aren’t connected to anything.
Currently, Roon is using “DSD over PCM,” but the channel 3+4 issue persists even when playing regular PCM content.
I also tried changing the “Channel Layout” in the advanced settings (e.g., from stereo to 2.0 or mono), but it didn’t solve the problem.
So, my two questions are:
How can I enable native DSD playback with this setup?
How can I disable output on channels 3+4 to avoid the unnecessary signal there?
How can I change the chanell layout from 2.0 to 4 chanells? Motu m4 supports 4 chanells, so I may use 3rd chanells for sub.
The Linux kernel on the RPi must have and activate a fitting USB driver for the DAC (not a Roon issue). Please look for support resources of the distribution you used for the RPi to ask about supported DACs. Then this native DSD support needs to propagate to ALSA properly as that is what Roon Bridge is using for local sound (on the RPi).
IDK if Roon is sending that or if it is some driver thing. If you have a software that can use those two channels, you can try and use them there – as Roon’s zone is set to 2.0 they should be free to use for other software.
NOTE: Roon supports 2.0, 5.1 and 7.1 (2, 6 and 8 channels) – but as can be seen from this listing, no 4.0 setup. See also:
As @BlackJack mentioned, the drivers needed for ALSA Rasberry Pi Native DSD and Windows Native DSD are different, I would look over the driver settings.
When the issue occurs, what does Roon’s Signal Path show? Can you share a screenshot? Does the same behavior happen if you plug the Motu into the Windows 11 PC and output to it via Roon?
Thanks for confirming that the issue only happens on RoonBridge/ALSA and not on Windows. I’ve activated diagnostics to see if the logs will tell us more clues about the exact channel outputs, but I see that your Roon Server isn’t currently online. Can you let us know next time you use it so that we can check for the log package? Also, can you provide a link to the other Community report? Was it for the same Motu device or for a different ALSA device?
here is a user saying the same:
"The only drawback is, that only two channels are supported by Roon (1+2). Channels 3+4 show a high playback volume but deliver nothing."
Same with my ADI-2/4 pro if I send stereo. But I use it with a convolution filter in Roon with stereo in and eight channels out (ADI has eight channels) and then there is signal on all eight channels. I guess this will work for the four channel of the Motu too.
I use the other channels for an active 2x2 system and the convolution filters realize the crossover.
What is your Use Case?
Edit:
I now read from the beginning of the thread. I think a convolution filter to run a mono or a stereo SUB on channel 3 or 3/4 should be easy to achieved.
Strange meter behavior like you’re experiencing is not uncommon with 4-channel stereo (4i/4o) class-compliant USB DACs like the MOTU M4 with RoonBridge. It’s partially for this reason that we don’t support 4-channel input officially with Roon.
Here’s what is most likely happening:
When this DAC initiates with RoonBridge, it activates on all channels - the driver will fill the empty channels with digital filler for either loopback or hardware interface purposes. Roon isn’t sending anything at all, there’s just no UI to specify channel routing, either in RoonBridge or within this ALSA setup.
Windows doesn’t have this issue because the USB connection and drivers involved are different.
I strongly suggest you copy/paste the bulk of your original post here into the Feature Suggestions category where the Product team and other users can consider it for future releases.
If the problem is connected to the driver, then why all the other renderers on raspberry (upnp, mpd, Spotify, airplay) work correctly?
Only with roon bridge in all raspberry roms exist this problem, so I think that this can fixed independently from the driver, otherwise all the other renders would have the same behaviour.
