Some notes to install and configure music services on a RaspberryPi running DietPi OS.
% aplay -l
In our case we can spot our USB DAC
card 1: m9XX [m9XX], device 0: USB Audio [USB Audio]
Subdevices: 0/1
Subdevice #0: subdevice #0
Configuration file on dietpi is /etc/default/raspotify
Look for the line with OPTIONS=... and stick the device plughw:<card number>:<subdevice>.
OPTIONS="--device plughw:1,0"
More info https://www.volkerschatz.com/noise/alsa.html
Configuration file is /usr/local/etc/shairport-sync.conf
Slighly different device string syntax, to see the device attached to your RaspberryPi, use
shairport-sync -h
And look at the bottom of the output after "hardware output devices:"
To restart shairport-sync, in case you made changes in the configuration file:
sudo dietpi-services restart shairport-sync
speaker-test -t sine -f 500 -D plughw:1,0
https://www.jackenhack.com/shairport-crashing-when-using-usb-dac-with-raspberry-pi/