I find the audio quality out of spotify (and the pi in general) really tinny.
I had a cheap USB soundcard, feeding into a yamaha amp via the cd line in.
Is there anything I can do to tweak the audio quality, a higher bitrate? The addition of some bass? I’ve tried doing it on the amp but is doesn’t have any options for changing the inputs
Get a DAC from Polyvection company and you’ll be golden. Problem is both your cheap card probably and compressed stream from Spotify. Test with Tidal lossless maybe…
Make sure you have Prefer Higher Quality Stream turned on in system. And your Dac could be the weakness, since it is a USB DAC you can try to connect it to a pc and listen to the result with high quality audio files.