spotityd.conf
[global]
username = "blahblah" <-----your account name
password = "blahblahblah" <----your account pw
device = "default:CARD=DSD" <------hw:....can not be used
volume-control = "softvol"
device_name = "Bedroom" <----text only what ever name you want
bitrate = 320
Also even though you seem to be getting sound 'without' enabling the kernel for I2S it still should be enabled to get the intended function of a I2S card. Note: all HATS function in I2S mode to communicate vs USB.
Also when you started the service, since its running as root, you can't include the --user in the systemctl line, per instructions.
systemctl start spotifyd.service
systemctl enable spotifyd.service