Short noise - Anthem STR Integrated Amplifier - USB DAC

Hello,

I have a problem with my Anthem STR Integrated Amplifier.
If I select the integrated DAC as the source and start playback, you can hear a digital noise for a short time, then it plays the music normally.
It only happens after the STR is switching on, not later.

My chain: ROCK (Intel NUC) - USB - Anthem STR

I ask the Anthem Support, here are the answer:
“The issue here is most likely due to Roon’s playback settings if you are having problems with both DSD (decoded by our DAC) and PCM (decoded by Roon/source). We can only verify the functionality using our tested setup using XMOS and Foobar2000. Can you install XMOS and Foobar2000 and try to play a native DSD file and see if it works?”

I do this Test with PC and Foobar, its play without the short noise.
What can I do? Are there any solutions?

Best regards sincerely
Michael

Go into device setup and adjust re-sync delay to see if that helps.

Default is - 0 ms
I test it up to 8000 ms - but no effect

I think it’s a buffer that is not empty.
Because it only happens when the STR is turned on.

Hello @Michael_Schmitt, and thanks for your report! I found a similar community thread outlining a known issue with Anthem STR when connected to a Linux USB. Let me know if this sounds like your issue.

Hello @nuwriy, no, it is not similar. This short digital noise can only be heard when I switch on the STR and start playback. Then he plays the music normally. Even if you press pause and play again, it plays normally. No matter whether pcm or dsd. The digital noise was not heard in the tests with Windows and Foobar.

Hello @Michael_Schmitt, thanks for the screenshots and the clarification here. I ran this thread and your issue by our QA team again, and they provided some feedback about the situation.
Unfortunately, as mentioned before, the Anthem STR does not support USB from Linux, so that’s where the issues stem from. There are a couple potential workarounds here that would help:

  • Using an S/PDIF to USB cable to connect to your Anthem device via S/PDIF. You’ll want to make sure you get one that supports DOP if you go this route. Note that we can’t guarantee DSD will work in this configuration with your device.
  • Install RoonBridge on a Mac or Windows device. The Anthem does support USB from these sources, so RoonBridge would be a good potential option here.

You have our apologies here for the inconvenience, Michael, but unfortunately, the Anthem’s Linux support is not something that can be changed on our end. If you have any questions about this please let us know!

Hello, I tried roon bridge on my PC, it works without the short digital noise after switching on the STR. PCM and DSD work normally. Thanks for your help.


What does that even mean? Linux has built-in support for USB Audio Class 2, just as macOS does. It’s a standard, not a per-OS variable.

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Does this also happen with PCM playback?

I was wondering if this was another case of the infamous XMOS firmware bug. My thinking is that the software initializes the XMOS USB input to a specific bit rate and sample size, and then the data coming down from the Linux box selects a different sample size, but same rate, so it triggers the bug. Which would explain why it only happens on start-up.

However, with that bug, the system hangs (well, the XMOS chip hangs) so it doesn’t sound like it is the right diagnosis.

Hello @Bill_Janssen,

Just because a USB chipset implements UAC 2 support does not mean that the device will be able to seamlessly play audio from any UAC 2 source. As evidenced by the “XMOS bug” and issues with “Push” vs “Event” mode in Windows WASAPI, the different UAC 2 drivers have different timing and order-of-operations characteristics as well as different ways of handling things like clocking and buffering. There are multiple opportunities for bugs in OS drivers or USB chipset firmwares to be exposed even though they are speaking the same “standard”. Then consider the possibility that the OS driver and USB chipset interface correctly but that the timing characteristics cause a problem downstream when forwarded from the USB chipset to the device mainboard.

There’s a reason the “Roon Ready” and “Roon Tested” programs were created: The only way to truly know if an audio device will work in a given setup is to test it.

-John

Am I reading this right? This is a significant issue for Anthem, IMO. Is the STR intended to be a DAC/amp only for direct computer-based setups? I think there are many of us out here that don’t use a direct PC to DAC interface for our audio systems. Many of the current streamers use Linux-based OS’s, and if the Anthem STR (or their Preamp) will not work correctly with a Linux-based USB input, then they are really very limited, in my estimation. I was seriously considering getting an Anthem STR; now I’m seriously reconsidering it. Anthem needs to get on the ball. Just sayin’ . . . :grimacing: :wink:

Sad but true! Thanks, John.

Indeed. Yes, there might be bugs in the device drivers for Linux, but given that lots of other XMOS-based devices work just fine with Linux and no special device drivers, I’d guess that this points to a shortfall somewhere in the Anthem STR firmware or hardware engineering. Perhaps there’s a firmware upgrade to address this?

no its hapen with dsd and pcm