Still not quite sure what's going on here. Most of the listening fraternity are siding with DACs, so I'm going to explain a little bit more about my set-up. I have a MacBook Air running Spotify and iTunes. I use Spotify to find stuff, then iTunes to buy it; compile a playlist and burn a CD (for the old car, like).
The signal leaves the 3.5mm headphone output and enters via RCA on Line 1 on my Roksan Kandy, circa 2002, which feeds a pair of Kef Concertos (also circa 2002).
If I read this right, a third party player like Pure or Decibel 'should' improve my iTunes files (PS What file format is iTunes), but if I buy a DAC, say a Dragonfly and feed the same 3.5 to RCA in exactly the same way, both iTunes and Spotfy 'should' sound better. Is that how it works? The existing set-up converts the digital file using the MacBook DAC whilst the Dragonfly would take a digital signal via the USB and process it 'better'. I mean surely a laptop's DAC is never going to be as good as one made by a company specialising in turning digital files to an analogue signal?
Anyway I tried Qobuz on the 320k mode and it knocked Spotify's socks off, so I tried their Hi-Fi service and to me this sounds better than iTunes, even on my ageing kit!