I had exactly the same requirements (deezer, tunein radio, streaming from backend server, etc.)
I have found that the combination of squeezelite and jive lite (both based on Logitech's open source squeeze player) fit perfectly. Squeezelite is for headless audio streaming, live lite is an optional graphical interface that works with raspi touch screens.
They are included in 2 raspberry pi pre-built packages that are really easy to install:
Both packages support most sound cards from hifiberry, iqaudio (I use both in my setup), cirrus logic and others (check first, of course).
I could not make the touch interface of jive lite work with piCorePlayer, but it still works well as a display. With max2play everything works fine (some tweaking required). You can also hack it together yourself on raspbian or arch Linux if you are so inclined.
The squeezelite/jive lite combo adds up to something that has much more functionality than what I expected. In fact, it is the best and most flexible multi-room audio streaming system I have ever seen, including commercial ones.
Here's a list of what you get:
- touch interface on raspi using jive lite
- remote control on Mac/PC/linux with jive lite or squeeze player (also provides playback)
- apps on iOS and android: squeezebox controller and ipeng
- web interface for playback (provided by Logitech media server)
- web interface for configuration (with max2pay or piCorePlayer)
- cast to raspi, pc, Mac, Linux, iOS, android players
- cast from raspi, pc, Mac, Linux with Logitech media server or squeezecast
- choose which source to use with each player
- play separately on each player, or sync any players to play the same thing
- very responsive to remote control (stop/start/volume change execute almost without lag)
Streaming services can be added to the system with squeezeplay "apps". For this you need a Logitech account though (it is free). The following services are available:
- Tunein radio
- ... and many other less known services
This adds up to the best and most versatile home music setup I've ever used, or in fact ever seen
you can use headless players, players with display and touch interface, any computer you already have, and integrate them into a single system wich you can remote control from anywhere, your phone, a pc you work on, anything. You can stream from any source you have. The interface is nice too. For each player, you can chose what sound quality you want, whether you want digital or analog output, amped or not amped, etc (of course, this is a flexibility afforded by the pi itself, not the software, but the software supports your choices). Heck, you can build a dedicated wall-mounted remote control for the entire setup wit the pi and a touch screen (which is my next project, and a quite simple one - I just need to buy a touch screen for one of my existing pi-s and install max2play on it to run jive lite only).
Hope this was helpful.