USB SPDIF Configuration?

[TheOldPresbyope]

@SerbJ 

I'm having trouble deciding what the Douk website is saying about your device but I do see words like "XMOS XU208" (which is the microcontroller which handles the USB interface), and PCM, native DSD, and DSD over PCM (DoP).

These put it in the same class as my Khadas Tone 1 Board which also uses the XMOS XU208 microcontroller to handle the USB input and, in this case, an onboard ESS ES9038Q2M DAC chip. There's no onboard PCM/DSD indicator or bitrate display such as the Topping DACs have.

My board has no trouble playing native PCM streams, native DSD streams, and DoP streams from moOde. Like many USB DACs in its price range, it offers hardware volume control only of PCM streams  so, like your device, it requires downstream volume control for incoming DSD streams. That's not a big deal for me because I have only a smattering of DSD-encoded tracks which I use mostly for testing purposes.

Out of curiosity, what output do you get when you run the alsacap command from the moOde command line?

Here's what I get

Code:

pi@moode837:~ $ alsacap
*** Scanning for playback devices ***
Card 0, ID `b1', name `bcm2835 HDMI 1'
 Device 0, ID `bcm2835 HDMI 1', name `bcm2835 HDMI 1', 4 subdevices (4 available)
   1..8 channels, sampling rate 8000..192000 Hz
   Sample formats: U8, S16_LE
   Buffer size range from 80 to 131072
   Period size range from 80 to 131072

     Subdevice 0, name `subdevice #0'
     Subdevice 1, name `subdevice #1'
     Subdevice 2, name `subdevice #2'
     Subdevice 3, name `subdevice #3'
 Device 1, ID `bcm2835 HDMI 1', name `bcm2835 HDMI 1', 1 subdevices (1 available)
   2 channels, sampling rate 44100..48000 Hz
   Sample formats: S16_LE
   Buffer size range from 444 to 32768
   Period size range from 444 to 32768

     Subdevice 0, name `subdevice #0'
Card 1, ID `Headphones', name `bcm2835 Headphones'
 Device 0, ID `bcm2835 Headphones', name `bcm2835 Headphones', 4 subdevices (4 available)
   1..8 channels, sampling rate 8000..192000 Hz
   Sample formats: U8, S16_LE
   Buffer size range from 80 to 131072
   Period size range from 80 to 131072

     Subdevice 0, name `subdevice #0'
     Subdevice 1, name `subdevice #1'
     Subdevice 2, name `subdevice #2'
     Subdevice 3, name `subdevice #3'
Card 2, ID `Tone1', name `Tone1'
 Device 0, ID `USB Audio', name `USB Audio', 1 subdevices (1 available)
   2 channels, sampling rate 44100..768000 Hz
   Sample formats: S32_LE, SPECIAL, DSD_U32_BE
   Buffer size range from 16 to 1536000
   Period size range from 8 to 768000

     Subdevice 0, name `subdevice #0'

As you can see, the Khadas Tone 1 is ALSA Card 2. It has informed Linux that it can accept 32-bit PCM (the S32_LE format) and 32-bit DSD (the DSD_U32_BE format).

ETA - I wrote the above without thinking. DSD is a 1-bit encoding scheme. That "32-bit DSD" refers to the way the bits are packed into bytes/words.

I have no trouble playing PCM tracks (such as my extensive collection of FLAC tracks) or DSD tracks through my Khadas Tone1. The ESS 9038 chip can accept either native DSD or DoP; my preference is to stream native DSD.

Here's what the "audio info" feature of moOde returns for a FLAC track I just played using hardware volume control (software volume control would have worked as well) -

Code:

INPUT / OUTPUT
Source          NAS/omv-nfs/Mostly-Piano_Ashokan-Farewell/Mostly Piano - 10 - Ashokan Farewell - 19224-FLAC.flac
Source format   FLAC 24 bit 192 kHz, Stereo
Decoded to      PCM 24 bit 192 kHz, Stereo, 6.104 Mbps
Output format   PCM 32 bit 192 kHz, Stereo, 12.288 Mbps
ALSA mode       Default (plughw)
Audio chain     MPD -> plughw -> DeviceDSP OPERATIONS
Resample rate   Off
Quality         Off
Selective       Off
CamillaDSP      Off
Volume type     Hardware (On-chip)AUDIO DEVICE
Device          Tone1
Mixer name      Tone1
Interface       USB
Formats         S32_LE, SPECIAL, DSD_U32_BE
Platform        Pi-4B 1.1 2GB

and a DSD track playing with mooOde's volume type set to "Fixed (0dB output)"

Code:

INPUT / OUTPUT
Source          NAS/OMV-Music/DSD/NDSD012/02_Welcome-to-NativeDSD-Sampler_NativeDSD-Presents_NDSD012_2ch64.dsf
Source format   DSD 1 bit 2.822 MHz, Stereo
Decoded to      DSD 1 bit 2.822 MHz, Stereo, 5.645 Mbps
Output format   DSD 1 bit 2.822 MHz, Stereo, 5.645 Mbps
ALSA mode       Default (plughw)
Audio chain     MPD -> plughw -> DeviceDSP OPERATIONS
Resample rate   Off
Quality         Off
Selective       Off
CamillaDSP      Off
Volume type     Fixed (0dB output)AUDIO DEVICE
Device          Tone1
Mixer name      Tone1
Interface       USB
Formats         S32_LE, SPECIAL, DSD_U32_BE
Platform        Pi-4B 1.1 2GB

Regards,
Kent