We have a new Pi 5 image, but it still doesn't work properly. The cause appears to be HifiBerry driver or hardware issues; we're seeing glitches, but not just with Stereo Tool, also with Linux' build-in player aplay. So for now it's probably not really usable. This seems to be triggered by memory usage; MicroMPX does appear to work fine (but I have only briefly tested it). Everything works fine on the Pi 4 with the same image.
In case you do want to test it:
https://download.thimeo.com/Thimeo_Pi345.zip
Quote:
The Thimeo PI Image will work but goes into reboot loops after configuring a Static IP.
Do you get any messages about the server not being started? If the image cannot start the web server, it reboots because the device would be inaccessible. Maybe something is wrong with the configuration? Such error messages - and possibly others - are shown if you connect a monitor.
Aside from this, your use case should work since it doesn't use a HifiBerry.