The debug info you posted indicate a failure in opening the ALSA device located at Card 1 (which - I suppose, going by the other thread you opened) - is the NAD D 3020 Hybrid amplifier).
Can you please try to switch to one of the Raspberry's native outputs in the MPD page and try again to playback one of your Spotify playlists?
If that works, then it could be that your amplifier working as a DAC is not correctly recognized in ALSA - in which case some more debugging will be needed.
Thanks.