· There seems to be an issue with RAAT following the latest Apple Tahoe 26.5.1 release
Tell us about your home network
· The Roon server is on a Dell R340 server running Linux Mint and connects to my 10G Mikrotik server over DAC cable. This is connected to a Mikrotik 10/1G switch over SFP which connects to my WAN via a pfsense router and to my Wifi devices through two AP's and to my Macbook via wired Ethernet. I have a 10G connection to my downstairs switch which connects to my Moon 390 preamp over wired Ethernet.
I can connect to the Roon server with ARC and my iPad and everything works well. My Mac worked perfectly up until a couple of days ago. I use a Chord Hugo2 or Chord Mojo. The system has been stable for many years.
Since the MacOS update I cannot play music through the external DACs on the Macbook. I can play music through the internal speakers of the Mac, but trying to start playback on an album to stream to the DAC audio zone results in the play icon next to the track name skipping down the list and then failing due to "too many errors". The RAAT system does get as far as setting the sampling rate of the DAC to 706kHz oversampling and then gives up. The DAC also works with other applications on the Mac such as Youtube and Audacity.
It looks to me like an issue with RAAT and the latest MacOS update
Thank you for the detailed description. Since you are running macOS, the behavior you are seeing may be related to the stricter Local Network permission controls introduced in recent macOS releases.
Please try the following:
Open macOS System Settings → Privacy & Security → Local Network
Make sure Roon and Roon Server are both enabled
Even if they are already enabled, try toggling them off and back on
If this does not help, please note the exact time of your next failed playback attempt and share it here so we can review the logs.
The Roon Server is on a separate machine. Checking local network access, I can see that Roon has access. This makes sense as I can play tracks on the Mac to its internal speakers, the issue arises when I play out via the USB DAC.
I last tried to play tracks which failed at 4:22 UK time (13:22 UTC) I assume you can access logs on my Roon server?
Thanks for the additional information! From a fresh server diagnostic report, we can see:
Whenever a track is sent to the Mojo (and from earlier logs, Hugo2) zone, which is the USB DAC attached to your MacBook, the server immediately throws flac encoder init failed: state=11 and aborts the stream. Roon retries each track, fails again, and after enough consecutive failures the UI gives up with "too many errors."
The exact same tracks play fine to the Moon 390 and iPad zones (no flac error). So the music files, the library, and the network path to the server are all healthy.
So it seems the failure is in the FLAC encoder initialization for the RAAT stream destined to the Mac, not in your network, switches, DAC cabling, or the server’s access to files.
The decisive detail: the failing setup request is almost always sample_rate: 705600, bits_per_sample: 32, wire_codec: flac (34 of the failures), plus one at 768000. 705600 Hz is 16× oversampling of 44.1k, the “706kHz” you saw the DAC being set to. The FLAC standard doesn’t support sample rates that high, and FLAC streams are capped at 24-bit.
The server is being asked to FLAC-encode a 32-bit / 705600 Hz stream, and the encoder refuses to initialise, state=11 is essentially “invalid/unsupported parameters.” The same tracks play fine to your Moon 390 and iPad because those zones aren’t asking for 32/705600.
Some next steps for you to try:
Check DSP / upsampling on the Mac zone. In Roon: Zone (Mojo/Hugo2) → DSP Engine → Sample Rate Conversion. If it's set to upsample to "Max PCM power of 2" or a fixed 705.6k, that's the trigger. Turn Sample Rate Conversion off entirely and try playback. If it plays, you've confirmed the cause.
Check Device Setup → "Max Sample Rate (PCM)" for that zone. Cap it at something the FLAC transport handles (e.g. 192000 or 384000). If macOS is now advertising 768k/706k as the device max, Roon may be auto-targeting it.
As a quick isolation test, force the transport codec. In Device Setup there's no direct FLAC toggle, but disabling upsampling (step 1) effectively avoids it. If you specifically want bit-perfect high-rate to the Hugo2, the real fix is keeping the rate within FLAC limits, the Hugo2 maxes at 768k DXD/PCM but RAAT's lossless FLAC wire codec can't carry 32-bit/705.6k.
We’ll be on standby for your reply and results, thank you!
Setting the sample rate conversion for 44.1kHz to 8x oversampling rather than 16x oversampling to 705.6kHz works. I can now hear music through the DAC.
Up until this issue, I had the Mac set up as 2n sampling to the maximum sample rate of the DAC. Playing back 44/16 audio resulted in an output to the DAC of 705.6/32 with either the Hugo2 or the Mojo. It worked, I could see the DAC running at 705.6kHz from the Mac Audio MIDI setup page - format 705,600Hz 32 bit. It has been stable for years.
Now, all of a sudden I have to drop the sample rate to 352.8kHz to be able to play back through a DAC that can oversample and DID oversample with the same system setup at x16? Why is that?
It worked and something has broken and I’d like to see a fix.
Thanks for letting us know. We enabled diagnostics for your Roon Server, and we can see that the issue is the same as the one mentioned here:
There is a fix in the works for this issue, I can’t comment on when the fix will be published, but it is being worked on. I will merge your thread into the tracking thread so that you are notified when there is progress. Thanks!
