At the moment I'm using my local music library almost exclusively from my mac, where I need to have it stored for DJ-ing purposes. My phone (an iphone) doesn't have much memory so I usually have very little music stored in there. I would like to be able to use my raspberry as a sort of extra local storing device that my phone would be able to stream so as to play it at home on some bluetooth speakers (or equivalently remote control the raspberry if I were to buy a bluetooth emitter that would connect the raspberry to my speakers).
The idea would be that the last version of the library is always on my mac, while the raspberry stores it on an external hard drive and upgrades it via rsync or something of the kind every now and then, or everytime I update my library.
I can't figure out if this is really the setup I want (but I think so), and I can't figure out an easy way to do this. I've looked into pi music box, volumio, various NAS things, but none seems to quite do the job.
Any ideas ?