[PROBLEM] Noise when playing first track via USB

[33AndAThird]

Whenever I turn on my pre-amp and play the first track there is a short (approx 0.25 secs) blast of noise. It does't occur again when I play other tracks, but if i turn either my PI4 or pre-amp on and off (effectively resetting the connection), it will occur again.

Signal Chain:
Airplay => Moode on RIP4 => USB => Anthem STR PRE => Musical Fidelity M2SI 
The USB implementation on the STR PRE is by XMOS.

This happened on 8.3.9 and I've just updated to 9.0.0 and the problem persists.

Any help is appreciated.

[Tim Curtis]

Why do you think this is a moode software issue?

[33AndAThird]

Why do you think this is a moode software issue?

Hi Tim, thanks for your reply and for a great music player project.

The reason is that other sources (for example my MacBook) don’t produce the same blast of noise when they start playing into the STR PRE over USB. 

The RPI itself is new, which I guess doesn’t mean it’s not a hardware issue, but I suspect if this was a hardware issue it simply wouldn’t work, rather than blast some noise on first play. I guess I could download a different music player and see if the same problem persists, which would give a bit more certaint?

[Tim Curtis]

When you play a moode radio station or the stereo test track or other music files does the glitch occur?

[33AndAThird]

When you play a moode radio station or the stereo test track or other music files does the glitch occur?

Yep, happens for the test track and radio stations as well as Airplay. 
Will happen every time I either turn the RPi on and off, or the STR Pre on and off.

[the_bertrum]

I've just had a quick look at the Anthem website. Very nice looking equipment. However their blurb says:
"This high-quality USB audio input transforms digitally stored audio from your Windows or Mac computer into warm, natural analog sound."
No mention of Linux. Perhaps a question to their support teams is in order?

[33AndAThird]

I've just had a quick look at the Anthem website.  Very nice looking equipment.  However their blurb says:
"This high-quality USB audio input transforms digitally stored audio from your Windows or Mac computer into warm, natural analog sound."
No mention of Linux.  Perhaps a question to their support teams is in order?

Thanks, I’ll do that. I think XMOS USB Audio is well supported by Linux, in that both are USB Audio 1/2 compliant (as per here https://www.xmos.com/software/usb-audio/driver-support/) but I’ll ask the question.

Thanks

[Tim Curtis]

Generally when a manufacturer does not explicitly state that Linux kernel <version> or higher is supported it means they don't test their products with Linux and thus there could be issues. IIRC some manufacturers use custom XMOS firmware that requires a custom USB driver, usually for Windows.

Like @the_bertrum suggested, ask the manufacturer but also ask them if they test against Linux and what version of the kernel do they claim should work.