Unfortunately we don’t have a Pi 4 with 8GB RAM yet, so we haven’t been able to test the image with it. So it may be that our Beta Buster Image is causing problems on this system. In itself, the Pi shouldn’t differ much from the 4GB version, but we cannot confirm with certainty that everything works until we have tested it ourselves. Our order was rejected until further notice, so we cannot say when we will receive a delivery with the 8GB version. However, as soon as it is available again, we will of course order it again.
To use the Pi only as a server, all you really need to do is deactivate the services in the audio player tab and remove them from the autostart. You could also deactivate the build-in audio in the Raspberry settings.