The RPi3+ Allo Boss Combo has recently undergone a Volumio upgrade so that I could sample the latest Tidal offer which was mentioned on here a few weeks ago.
Big thanks to whoever mentioned it, very impressed so far. Not only is it possible to download albums onto your phone, it's also possible to play tracks through the Sonos. Not realising any of this beforehand sort of put me off as CD's in particular get a lot of use when in the car. Time will tell but CD buying days could almost be over.
Downsides - The Volumio app is a bit clunky but options seem to be limited when using a Pi based streamer.