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Audio stutters with USB Dacs on Macbook M1 Pro

Ulfgard

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I need help getting external DACs to work correctly on my 2019 Macbook Pro M1.

I experience audio stutters as soon as I have a high system load. The stutters occur once every few minutes, each lasting only very short. The audio quality itself is excellent, and the DAC itself work fine.

The problem happens with the following DACs:

- Topping E70
- SMSL SU-8
- iFI Zen V2
- My USB-C-based Qudelix 5K Dac works fine, though - no issue at all.

Things I've tried:

- Change the audio format in Audio Midi Setup - no difference
- connect the DACs to a different USB port - either on a passive USB 2.0 Hub that is linked to my Thunderbolt Docking Station or going to the Thunderbolt Docking Station directly
- Restarting and updating the firmware (where possible)
- Disabling "Set time and date automatically" - this seems to improve the stutters minimally
- Try different audio sources (they all stutter)
- Using Bluetooth Audio output - this works fine.

The problem is undoubtedly related to the Macbook because a Windows Laptop has no issues using the DACs with the same setup/docking station.

If I had to guess, my Mac has an issue with the USB 2.0 port, which is the common connector of all DACs (except the Qudelix).

Do you have any other ideas of what I could try? I'm at my wit's end, ordering several DACs from Amazon to see if one device magically works.
 

mocenigo

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I think this is to be expected. As soon as the machine pages, you can have stutters. This is not limited to macOS.
 
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Ulfgard

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My DACs work on Winows with absolutely no issue.
My Quedelix 5K (USB-C product) also has no issues to play music properly, no matter the system load. The MacBook loudspeakers also don't crackle.

I'm guessing the issue is somehow related to the USB 2.0 connection of the devices. But what to do, since all desktop DACs use that connector?
 

Dunring

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I have USB C to B cables, I'd try getting one instead of the stock 2.0 cable and see if that clears it up if you have C ports on it. An adapter works too, I get 3 packs of them on Amazon. I'd try a cable just for simplicity.
 
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Ulfgard

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I connected my SMSL with a USB-A to USB-C adapter to the MacBook. System information now lists the device under the USB 3.1 bus, which is what I wanted. However, the problem prevails.

Do you think trying a different cable will make a difference?


Looking through old forum & reddit threads, I now installed an equalizer (eqMac). Routing the audio output through the eqMac device seems to improve the audio output a bit.
I still get some stutters, but less than before. Edit: Audio improvement is less than I hoped for.
 

staticV3

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Do you think trying a different cable will make a difference?
No. USB 3.x/Thunderbolt chipsets causing stutter for USB 2.0 Audio is a common occurrence.
Afaik it can only be fixed if the manufacturer of the chipset patches the core issue.

Have you tried contacting Apple Support? They're usually very responsive. The more people contact them about this, the higher the chance they realize this is an actual issue that needs investigation.
 

beren777

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No issues on my older non-M-series Macbook Pro, but I'm also not using it for much esle but streaming. I did have stutters with it previously, but I traced them down to a wonky wifi connection.
 
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Ulfgard

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No. USB 3.x/Thunderbolt chipsets causing stutter for USB 2.0 Audio is a common occurrence.
Afaik it can only be fixed if the manufacturer of the chipset patches the core issue.

Have you tried contacting Apple Support? They're usually very responsive. The more people contact them about this, the higher the chance they realize this is an actual issue that needs investigation.
I tried a couple of different cables I still had lying around. It did not improve things.

What puzzles me is that I don't find many reports about this issue. The M1s are almost two years old now, I would be expecting more problem reports. I'm still waiting for a magical solution, maybe one of the new DACs I have incoming will work?
 

staticV3

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maybe one of the new DACs I have incoming will work?
The Qudelix is a UAC1 device while your other DACs are probably all UAC2.
Following this, you could try to get a DAC that is also UAC1. Chances are it won't stutter, just like the Qudelix.

The only desktop DAC with UAC1 mode that I know is the JDS Atom DAC+ with the UAC1 fallback cable that JDS sells separately.

Edit: another potential workaround is to get a PO100 Pro, set it to UAC1 mode, connect it to your MacBook via USB, then plug whatever DAC you'd like into it via Coax or Toslink.
The Hifime UT23 might also work for this.
 
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Ulfgard

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The Qudelix is a UAC1 device while your other DACs are probably all UAC2.
Following this, you could try to get a DAC that is also UAC1. Chances are it won't stutter, just like the Qudelix.

The only desktop DAC with UAC1 mode that I know is the JDS Atom DAC+ with the UAC1 fallback cable that JDS sells separately.
I don‘t know what UAC1 and UAC2 mean but I‘ve tried the „SABAJ A10d“ before - this DAC has a menu option to switch between UAC1 and UAC2. Alas no success. It even connected with USB C, but the device was still listed as a USB 2.0 device in the System Information browser.

My next DACs will be the iFi Uno and the new Soundblaster X5. Both connect with USB C and have the RCA outputs that I need.
 

DVDdoug

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It's not a common problem when playing audio (more of an issue with video) but usually it's related to multitasking & interrupts. It could be another application, driver, or background process... It's usually "something else" messing-up the audio...

The operating system is always multitasking even if you are only running one application so there is a buffer. During playback the buffer gets filled in a quick burst and the audio flows-out to the DAC at a smooth-constant rate. If something hogs the system for a few milliseconds too long and the buffer doesn't get re-filled in time you get buffer underflow and a glitch. It doesn't have to be using lots of total CPU time, it just has to hog the system a little too long.

.

..When recording, there is a recording buffer that works the other way. Data flows-in smoothly and it gets written to the hard disc is a quick burst. Here the danger is buffer overflow if it doesn't get read in time.
 
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Ulfgard

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It's not a common problem when playing audio (more of an issue with video) but usually it's related to multitasking & interrupts. It could be another application, driver, or background process... It's usually "something else" messing-up the audio...
I have a 16GB M1 Pro Laptop. The issues occur around „66% Memory pressure“. Whatever that means, it happens very quickly. Starting a Java IDE, running some AI background task - nothing that would bring the Macbook to a sweat, or even the fans to a run. Yet it‘s enough to reliably distort my desktop listening experience. This is not a normal load issue, this is a pretty annoying bug in the operating system. Propably related to its scheduler or something. Don‘t care. It used to „Just work“. Which it still does - using USB-C, direct headphone out, Blutooth or with the builtin speakers.
 
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Ulfgard

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Just a quick update:

- I managed to procure another UAC1-compatible DAC. However, I cannot get it to work. My Mac doesn't recognize it. Figure I need a special cable for it?

- Anyway, here is some slight progress:
I rewired my setup, so now I have: DAC -> passive USB 2.0 Hub -> another passive USB 2.0 Hub -> going into the USB 3 port of my Thunderbolt Docking station -> connecting to the Mac via Thunderbolt.

This setup greatly reduces the number of stutters under system load (compared to leaving out the daisy-chained USB hubs).

My "old" SMSL USB2.0 DAC has longer stutters than the new Topping E70. It still needs improvement, but the distortions went from several per minute to one per five minutes or so.


Does anybody care to explain what I'm doing?


Anyway, I'm still waiting for some USB-C DACs to get rid of that Frankenstein setup.
 

Axo1989

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I need help getting external DACs to work correctly on my 2019 Macbook Pro M1.

I experience audio stutters as soon as I have a high system load. The stutters occur once every few minutes, each lasting only very short. The audio quality itself is excellent, and the DAC itself work fine.

The problem happens with the following DACs:

- Topping E70
- SMSL SU-8
- iFI Zen V2
- My USB-C-based Qudelix 5K Dac works fine, though - no issue at all.

Things I've tried:

- Change the audio format in Audio Midi Setup - no difference
- connect the DACs to a different USB port - either on a passive USB 2.0 Hub that is linked to my Thunderbolt Docking Station or going to the Thunderbolt Docking Station directly
- Restarting and updating the firmware (where possible)
- Disabling "Set time and date automatically" - this seems to improve the stutters minimally
- Try different audio sources (they all stutter)
- Using Bluetooth Audio output - this works fine.

The problem is undoubtedly related to the Macbook because a Windows Laptop has no issues using the DACs with the same setup/docking station.

If I had to guess, my Mac has an issue with the USB 2.0 port, which is the common connector of all DACs (except the Qudelix).

Do you have any other ideas of what I could try? I'm at my wit's end, ordering several DACs from Amazon to see if one device magically works.

I've previously read about an issue with USB audio related to the T2 chip introduced in 2018 (that chip includes an audio controller function). I can't verify that specifically, but I have an M2 MacBook Pro and certainly experience what you are describing. When (say) Safari loads up and memory pressure is taking a hit, the stutters are quite apparent. Opening a new page in Safari or even scrolling an existing one will reliably trigger it. Quitting the browser and reducing the memory load fixes it.

Didn't happen with my previous Intel MacBook iirc. I've had a quick look for a Terminal fix to set audio playback priority higher, but no luck so far. Seems like a no-brainer as I'd rather almost anything else takes a millisecond or three longer instead of an interruption to audio playback. Anyway guess I'd best talk to Apple support as @staticV3 suggests.

I have a dock (part of a LaCie drive) in-between the laptop's Thunderbolt port and the DAC's USB-B input, so I should try a more direct connection to be sure, but as the issue seems to be new with the M2 Mac I don't think that's it.
 
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Ulfgard

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I've previously read about an issue with USB audio related to the T2 chip introduced in 2018 [...]
Yes, I stumbled upon those threads as well. That's where I have my idea to use passive USB hubs.

According to my understanding, the particular bug was fixed and lots of people with M1 Macbooks are happy using their external DACs.


May I ask how you get an audio signal out of your Macbook now?
 

Axo1989

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Yes, I stumbled upon those threads as well. That's where I have my idea to use passive USB hubs.

According to my understanding, the particular bug was fixed and lots of people with M1 Macbooks are happy using their external DACs.

Ok, I realised I'm still running 12.6 Monterey so maybe things will improve. I usually wait a few point releases before the annual upgrade but I'm a bit tardy this time round. But the issue doesn't really arise until memory pressure goes up.

May I ask how you get an audio signal out of your Macbook now?

Apple Thunderbolt Pro 3 metre cable to Thunderbolt port on LaCie 1Big Dock then USB-A to USB-B cable to ExaSound DAC (iirc it's the short cable supplied with the DAC). So active TB cable and active/powered dock.
 

Zek

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@Ulfgard What audio player are you using?
Maybe some settings in the audio player would help.
 
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Ulfgard

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@Ulfgard What audio player are you using?
Maybe some settings in the audio player would help.
It happens with all audio output, including Tidal and Apple Music. No software setting has improved it so far.
 

droid2000

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I had the same problem with a Macbook M1 Pro with a USB connection to an RME ADI-2 DAC.

This is a cheap and simple solution that worked for me (requires that you are using Roon though):

- install RoPieee onto a Raspberry Pi
- plug the Raspberry Pi into the DAC via USB
- the Macbook communicates to the Raspberry Pi over ethernet

Has never dropped since.
 

voodooless

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Curious issues. I’ve had zero issue with my M1 Max under any load with several devices.

Under what specific load does it occur? Is this sample rate dependent? Does it happen more often with a higher sample rate? Does it happen with all audio? Or only specifically from a single application?
 
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