Sorreltiger:My V-DAC does sound very nice indeed, with excellent imaging - that was probably the biggest improvement of all. I reasoned that a modest purchase was OK for Spotify listening! Although the V-DAC is a functional little black box, it can be hidden away!
Thanks for that info - I was wondering if a V-DAC would make a difference to a rather top of the range Yamaha Receiver, given that it already has decent on-board decoding.
Anyway, I have just swapped my airport express for the apple TV. I can't be sure, but I detect a slight deterioration in the audio quality. (nothng else changed, i.e., same optical cable, same input on my receiver). Maybe I need to give it a bit more time.