Is is possible to join Apple Music without them touching your ITunes library?
I once tried ITunes match and had to reload all my CD's as they deleted some and replaced with what they found was a match and I don't want that to happen again. (I have a lot of CD's from different parts of the world).
iPad Air
But that's the main reason I joined AppleMusic. I have 2 TB of tunes, maybe a third of which is stuff not *in* Apple's library, including many special CDs and lossless stuff downloaded for places like Dimeadozen. I ripped the CDs and converted downloaded FLACs, all to AppleLossless (ALAC). I have then synced all to my iCloud AppleMusic library.
When I first did it the sync took almost a week but once done, 1) at home I have everything available to me in lossless and 2) when away from home I can use iOS Music to play them all - the stuff that Apple had in lossless, the rest (the special CDs and otherwise stuff I've downloaded) in hi-quality lossy.
Apple Music vs. personal library
