That is indeed really cool, thanks for sharing! It inspired me to install Debian Bookworm(x desktop + vnc) and hqplayer 5 and it is indeed running smoothly up to 768 pcm(maximum of my Chord DAC). I can't get DSD 256 running without hickups though (DSD128 is fine). If you say headless, are you having an X desktop installed and are you accessing it via VNC? I prefer to run Debian in minimal configurationm without X/GUI, but the HQPlayer app seems to rely heavily on GUI depdencies. I tried HQplayer embedded on the RPI5 too, since that might perform even better. But it isn't starting, assuming it is still for RPI4 only.
I am also wondering which filters you are using for DSD 256? Thanks
In order to run embedded, you can install the Rasbian OS lite 64bit without GUI, you will need to download the Bookworm version of hqplayerd (NOT the embedded image that boots with USB drive).
you will need to install three packages libgmpris_2.2.1-11_arm64.deb, libsoup-3.0-0_3.4.4-1_arm64.deb and libsoup-3.0-common_3.4.4-1_all.deb
make sure you run the command line "sudo apt-get install -f " that will make sure it also install all the required dependencies.
With embedded (trial license), I was able to run DSD256x48 with default filters and the 7EC UL modulator. Try to play around with nblocks settings with a lower number between 1 to 4 to help with cpu disk cache (sudo nano /etc/hqplayer/hqplayerd.xml)
For oc settings I had forced_turbo=1 and that helped a bit too
Got to admit with embedded you are getting yourself in more diy categories rather than simple plug and play …
I don't have an embedded license. I have a desktop license, so I mainly just use the bookworm desktop version with x desktop + VNC and that only works for DSD128 or DSD256 (with non 7EC modulator)...
But with the Chord dacs, there is no reason to do upsampling to DSD since chord dacs do not do native DSD. Any DSD source fed to the Chord dacs get converted back to PCM 705.6khz or 768khz by the dac itself.