Re: High bitrate USB DAC performance with moOde

[TheOldPresbyope]

While perusing the Raspberry Pi Hardware documentation I came across this interesting note

Esoteric USB sound cards

Expensive audiophile sound cards typically use large amounts of USB bandwidth. Reliable operation with 96kHz/192kHz DACs is not guaranteed. As a workaround, forcing the output stream to be CD quality (44.1kHz/48kHz 16-bit) will reduce the stream bandwidth to reliable levels.

My only candidate is a Khadas Tone 1 board which is rated for PCM up to 384kHz @ 32bit and DSD up to DSD256. I haven't noticed any issues with it attached to Pi 4's and Pi 5's. (Candidly, however, I don't have much high-bitrate source material to test with.)

I'm curious to know if other moOde users have experienced "reliable operation" issues with their USB DAC that might be traced to using large amounts of USB bandwidth. If so, which DAC, which Pi model, and what sort of interconnection (via direct cable, via a USB hub, etc.)

Regards,
Kent

[Tim Curtis]

Thats a strange statement in their documentation.

If you want to test PCM just set SoX resampling to 32b 384k.

No issues on my end with Allo Revolution DAC and high bit rate PCM, DSD128/DoP or native DSD up to 256.

[Skip Pack]

I second Tim's response -- I've sent up to 384K PCM to USB Dacs mostly upsampled via SOX and at least one album from that high a resolution file without a problem.

Quick edit: This was using an RPi4B 4GB.

Ski

[DRONE7]

I've not experienced a problem (having used MoOde from day one and PI-1 upwards and far too many DACs).

I expect that as RPi is generally documented with their Desktop OS in mind then they are covering all options with use of associated USB hardware.
So running the Full Desktop, mouse, keyboard, any other USB devices and a DAC may apply to their advisory.

Luckily, MoOde being headless and based on RPi OS lite, we are probably not impacted by that. :-)

[TheOldPresbyope]

I don't disagree with the above.

Also, I would expect the issue more likely to occur in earlier model Pi's, given the I/O architecture of the Pi 3 and below with all USB ports and ethernet port sharing a single internal USB bus (and, as I understand it, with high speed USB being limited to 280 MB/s instead of the usual 480 MB/s).

Anyway, I thought it interesting that the hardware docs didn't qualify this note by either model types (as is true in other portions of the docs) or RPiOS vs RPiOS Lite.

Regards,
Kent