More mind-blowing distortion on Roon FLAC files

I need to restart a similar thread that seems to have been closed on December of 2018 (but not resolved, in my opinion). I am new to high-res streaming and I am now getting a loud screeching distortion when I pause a track, then resume it a few minutes later. This does not happen on all tracks, but I have noticed it on streamed FLAC files from both Qobuz and Tidal. What’s extremely peculiar is that the same thing is happening on Audirvana. The two players have different sets of settings and I cannot find any setting that would be causing this. I can shut down both players, restart them, and if I resume the same track, the distortion continues to happen. I have a pretty high-end DAC and headphone amp that I’ve also shut down and restarted. Same thing. I’m running on a MacBook Pro (with either power adapter or on battery) and as far as I know, I have the settings on both players to avoid any involvement Apple might have in manipulating the music between the players and the DAC. I’m also using a premium $400 solid silver USB cable between the Mac and DAC. As far as headphones go, I have several sets that I’ve exchanged, with no resolve. What could be causing this? There are way too many variables for me to test any further. And it makes no sense that these files are coming from different sources and happening on two different players. It’s also not always the same track. My mind is blown (as well as my eardrums). And I fear for the safety of some expensive equipment. I have a lot invested in this setup and I would hate for it to be a waste. This has been happening at least once each time I use the rig. One last thing. I’m not 100% sure this only effects FLAC files. But I do believe they’re only high-res, thus far. Thanks for any help I can get. Could this have anything to do with upsampling?

I’ve moved this to support. It would be helpful if you list your equipment in detail.

As I understand it, you are experiencing this distortion only on streaming hi res FLAC content but not local files ? And on both Audivarna and Roon ?

The common factors would seem to be your network and DAC. Can you describe them ?

One possible source for such are audiophile USB cables which rarely meet USB specifications due to strange construction, and thus don’t have the USB HiSpeed certification badge either. When buying cable, look for these:

At least trying with another, standard cable is cheap ($10/10€).


Thanks for the input. My MacBook Pro is only a year old. So I am going USB-C to USB-B using a Silver Dragon cable from Moon Audio, where I also purchased my “Questyle CMA Twelve Master” DAC and headphone amp unit (which is one of their flagships with great reviews)—not that there couldn’t be a problem with it. I find it hard to believe this would be the USB Cable, though. It’s too intermittent and only happens when I pause a track, then restart it a few minutes later (at least from my poor memory). And it would also seem this would also be happening from my library FLAC files as well, which are stored on an Synology RackStation RS1219+ using an HP(E) Aruba 2540 10GB 4SFP managed switch (sorry… you asked for all of my equipment!). My headphones (which I’ve interchanged to find the same problem on all of them) are HiFiMan Sundara’s, HiFiMan and HE1000se’s which share Forza Audioworks “Hybrid” copper/silver cables, and an older pair of AKG Q701’s using stock cables. I’m running no other audio software other than Adobe Cloud video production apps. Am I missing anything? I’m sure! But nothing I can think would interfere. I still question if this could be an upsampling problem, which is the only common setting on both players. I have not had a chance to check this out. I thought I would run this by the community before I go f’n up all my settings which took me forever to research. But I’m not stubborn. I’m open to, and grateful for ANY ideas you all might have.

Also, I’m not aware the Silver Dragon USB cable carries any of those logos, but I do know they’re 3.0, which should meet the criteria.

It sounds like a data transfer problem on the USB. USB Audio Class doesn’t have error correction, so transfer errors cause audible problems.

I see two possibilities, one is the cable (easy to test with a cheap standard cable). Another is known problem related to the T2 security chip. You can find a lot of information about it around the net (but you cannot do much about it):

They’ve been trying to fix it, with possibly limited success regarding corner cases. Mostly solution has been to use Thunderbolt-based dock that has it’s own separate USB interface implementation inside.

Third possibility is aggressive power saving dropping the USB into powersave state and then wakeup failing.

This also almost seems like it could be a caching issue, if you ask me. The starting and stopping it is what catches me. But now that I think about it, it seems to effect the whole album once it happens to that particular track, which opens up a whole new can of worms because the whole album doesn’t download at once. I cannot be 100% sure on this right now and tonight I have to call it quits and hope some ideas pop up by tomorrow afternoon. FYI, I have 2Gb download speeds using an Argus Surfboard modem.
Thanks again!

But wouldn’t this problem have come up on the support site before now???

And my MacBook Pro is a 2017 model.

At least this T2 glitch has been discussed a lot about 6 months ago on many forums, at least on AS and Apple’s forums. Maybe here too, but I’m not able to follow everything here.

You are using wired ethernet? Or wireless? Wireless could cause interference on problematic USB cable at transfer peaks.

Also, I’d strongly recommend that you check your switch configuration that it has 802.3x ethernet flow control enabled (default setting in smart switches vary). Otherwise any device not capable of 10 Gbps sustained speeds experience massive packet loss and resend storm (wireless being example of such)…

But the cable is DEFINITELY worth testing. I wish I had gotten a split/dual cable (keeping the power line separated). My other alternative is getting an iFi USB conditioner that also reclocks the wave signal (which could also be part of the problem, but that mostly resolves jitter). I will be checking this out tomorrow.

Switch config check for 802.3x is quick and easy, could be related to the USB behavior due to the involved traffic patterns.

You are awesome to stick with this on me. Thank you!. And I will check out the switch. I am using Ethernet, but only Gigabit on the MacBook Pro. I use the 10Gb on my NAS and two Mac Pros. (I run a business out of my home.) Thanks again Jussi. Again, I will follow through with all of your recommendations!

Nope. Using that logo requires some effort to conform and test to standard specs as certified by an outside body or they can’t use it.

Before anything else, get a normal usb cable and try it first, quick easy and cheap to test.

I have this issue with one of my DACs when connected via USB directly to an iMac. It’s a problem between the Mac and the DAC not syncing bitrate properly so the DAC decodes as garbage. I can make the problem go away by locking the Mac to a specific bitrate (using MIDI settings) but then you’re not “bit perfect” to the DAC unless what you’re listening to matches obviously.

It gets worse the “busier” the Mac is. A reboot of the Mac makes it less frequent. It’s also less frequent with any software that can use the DAC in “exclusive mode” (including Roon, make sure you’re using it this way).

Anyway, I blame the DAC honestly. And, if you read enough reviews + user experiences you’ll find $$ does not guarantee no problems. First thing I’d try, in your set-up, get a high quality generic and compliant USB cable and see if that helps. Good luck.

Would be good to find what, if any, common denominator there is.

I have three Macs and I commonly play both streams and local content with them, at very high CPU loads (due to HQPlayer upsampling), but I have not yet experienced such issues. And I’ve been doing this with various different DACs, at least 10 different ones.

I have one DAC that exhibits similar problem - Chord Mojo, but that happens with it eventually regardless if it is connected to Mac, iPhone or something else. But I’ve also found how soon it happens largely depends on the particular USB cable used.

Hi @Daniel_Rathje,

There have been some good suggestions above, testing with a different USB cable is a good troubleshooting step. I have another test in mind that’s even simpler and doesn’t require any hardware modifications though.

If you connect your headphones to the 3.5 jack on your Macbook Pro and send Roon’s audio stream to the “System Output” zone, do you still experience the same behavior?

This test will allow you to separate weather the issue is happening on the Macbook side or somewhere further down the line.

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Thank you all for your responses and great ideas to do some trials. Yes. It could be the DAC. It could be the cord. And I still think it could have to do with upsampling. It’s interesting to find out that others are having similar problems, but have found different reasons for them and/or solutions. If I have a USB-C to USB-B cord on hand, I have no way of knowing if it is compliant. But I can at least perform the 3.5mm jack test later today and get back to you. I’ll be miserable using Apple’s DAC after hearing the quality of my higher-end one with a decent amp. But at least I can get a start on testing this out. As far as the cord goes: 1) we’re in the middle of a bad snow storm; and 2) it will probably require ordering one, since we do not have very decent computer stores anywhere near. We’re in the middle of a the woods, near Lake Superior in Minnesota. If the 3.5mm works, I’ll post my results in the next day or so. But it won’t be until next week before I can nail it down to the Silver Dragon cable or DAC. Damn; I would hate to see it be my DAC! It was difficult enough finding a decent desktop that met my criteria. But honestly, the DAC was the first thought that came to mind when it happened the very first time. May I ask you all which brand/version of cords you aren’t having any problems with? Is anyone using an audiophile-grade cord without any problems?

I have one more question, though. Why would it have to do with particular tracks—especially when pausing them—and not others? And it doesn’t seem to have anything to do with the quality of resolution, either. So that right there may kill my upsampling theory.

An AmazonBasics cable will do fine. No need for “audiophile” for that particular connection.