Chromecast Audio is a great and very affordable starting point at $35. Analogue output is pretty good at Spotify resolutions. If you like it you can always later use its optical digital output and invest in an external DAC (the DAC is where the sound quality variable resides). See here for a serious test: http://archimago.blogspot.nl/2016/02/measurements-google-chromecast-audio_27.html
Enjoy.
Enjoy.