[Bug]: Xone db:2. Beep on device startup. Noise when playing sound (with afplay)

[soulcheck]

Pre-Submission Checklist

• I confirm this is NOT a code signing / certificate error.
• I have attached the log file (required for bug reports).

Describe the Bug

Hi!

Thanks for all the work bringing the devices back to life!

I'm trying to use the hal driver on mac (2021 m1, on tahoe 26.2).
I can't get it to work.

When i install it and power up the device i hear a beep on channels 1, 3 and 4 (channels as in mixer channels, not stereo channel). Channel 2 is silent. It lasts for minutes, then stops.

If i try to afplay /System/Library/Sounds/Funk.aiff while it's beeping i hear noise (as if audio bits were all scrambled).

If i do it after the beep stops, no sound is emitted.

Device Model

Allen & Heath Xone:DB2

Operating System

Other

📎 Attach Debug Log (REQUIRED)

Ozzy_Debug_Log_2026-01-12_20-22-09.txt

[mischa85]

Hmmm. This is very weird as the DB2 has the same hardware as the DB4 I'm testing on.

Is this still happening on the latest version?

[soulcheck]

With the latest version audio device isn't showing at all in audio midi setup.

kexstat list the kext as installed:

263    0 0                  0xb45      0xb45      com.ozzy.kext.OzzyKext (1.0.0) 449C54B5-88B1-35C3-9A8C-33DD065C4841 <66 4 3>

ioreg says the mixer is plugged in fine:

  +-o AppleT6000USBXHCI@02000000  <class AppleT6000USBXHCI, id 0x1000003d3, registered, matched, active, busy 0 (24 ms), retain 45>
  | +-o Allen&Heath Xone:DB2@02100000  <class IOUSBHostDevice, id 0x1000015b1, registered, matched, active, busy 0 (5 ms), retain 14>
  +-o AppleT6000USBXHCI@00000000  <class AppleT6000USBXHCI, id 0x100000389, registered, matched, active, busy 0 (20 ms), retain 39>

Logs do seem to suggest that the driver at least initializes:

-----------------------------------------------------
OZZY DEBUG LOG - Tue Jan 20 08:10:51 CET 2026
HISTORY (Start - Last 2h)
Timestamp               Ty Process[PID:TID]
2026-01-20 07:57:45.771 Df com.apple.audio.Core-Audio-Driver-Service.helper[2736:c7ea] [OzzyHAL:plugin] [OzzyHAL] Init
2026-01-20 08:00:07.149 Df com.apple.audio.Core-Audio-Driver-Service.helper[1949:4003] [OzzyHAL:plugin] [OzzyHAL] Init
2026-01-20 08:02:22.159 Df com.apple.audio.Core-Audio-Driver-Service.helper[610:165e] [OzzyHAL:plugin] [OzzyHAL] Init
2026-01-20 08:09:47.782 Df com.apple.audio.Core-Audio-Driver-Service.helper[3176:76b1] [OzzyHAL:plugin] [OzzyHAL] Init
2026-01-20 08:09:58.527 Df com.apple.audio.Core-Audio-Driver-Service.helper[3204:79b4] [OzzyHAL:plugin] [OzzyHAL] Init
HISTORY (End)
-----------------------------------------------------

[mischa85]

Forgot the USB IDs. Sorry about that.

36b0ccc

[soulcheck]

Alright! Thanks for the quick fix!

Now we're back to the original problem.

Ozzy_Debug_Log_2026-01-20_09-46-05.txt

Here's what I'm experiencing now

1. When i power up the device it starts beeping, the beeping continues for a while.
2. I used afplay while it was still beeping (this corresponds to the first StartIO/StopIO pair). I heard noise.
3. After some time the beeping stopped, the mixer went silent.
4. I triggered afplay again just to check (second StartIO/StopIO), this time nothing could be heard.

I powered the mixer off/on again twice, the second time i used afplay afterwards, but no sound came out.

[soulcheck]

Hi @mischa85!

I managed (well, Claude Code managed) to fix the beeping and play a sound correctly after analyzing a capture made on a Windows machine.

I've opened a draft PR. My CPP is rusty so I can't pretend i understand everything that happens there, but maybe it'll help.

Attaching the capture which i used to debug it:
db2.pcapng.zip