I'd be interested in hearing the full version of Spotify streaming at 320kbps.
If it's a true 320 by the time it gets to you (I suppose your internet speed would play the largest role), there will be no discernable difference between it and CD.
I listen to Spotify (£9.99 PCM) over my hifi. A Sonos media renderer outputs to a Moon DAC, then to my Class A amp and finally over speakers. Spotify can sound very good on the best recordings which have been mastered well. Quick A/B comparison does show that CD sound has greater depth and more "air" around instruments. There's better separation between instruments. How clearly this difference is heard does depend on the original recording. I've been using Spotify about 5 months. I'm not buying less music on physical formats.
Hmm - interesting. I'm not using Spotify via the hi-fi but if I did ever add a Naim net-enabled gizmo no doubt my 'position' on this might change.
For the moment, I'm happy to stay with things as they are. More than enough damn formats as it is !
Forgot to add that I'm too damn tight to splash out the £9.99 a month from Mosaic money. Not to mention that here in Wurzel-land we don't get 30MB/s, more like 2MB/s