This took me a while to figure out this morning so I'm going to pass a few tips on for others.
Context: I have lots of music stored on my PC. I normally just want a small selection of that music on my phone.
On previous phones I did the usual thing... drag and drop music across to the device or sync playlists from Media Player.
On my first WP7 device I started using Zune, but found it too slow and clunky and difficult to use. I wanted a Zune Pass so I could just get whatever music I wanted for a monthly fee, but this was not available in NZ.
I was also disappointed that Nokia Music never arrived here. I looked at 7Digital and a bunch of other music services, but most are either just for streaming music or are per-song purchasing stores... and none integrated properly into the WP Music hub.
Then Spotify was made available in NZ earlier this year and so I used that. The Spotify/Zune Pass idea suits me very well, but the WP Spotify app is incredibly buggy and from their own forums it is clear the devs couldn't care less about it.
Enter the Lumia 920 with Windows Phone 8 and the Xbox Music Pass. This service combines iMatch cloud matching/streaming, Spotify all-you-can-eat for a fee, iTunes per-song purchasing, and Pandora/Nokia Music streaming in one, and all in the Music hub... just what I wanted.
Best of all, the Xbox Pass is available in NZ... though oddly, Nokia Music is still dead on these phones.
So.. plugged it all into my Win8 PC and found that my phone started filling up with thousands of tracks from my PC library. Couldn't get rid of them so I wiped the phone and started over after disabling an option in the PC Music app to "sync music from my pc to all devices". That stopped the sync, but the phone still filled up with a large and seemingly random selection of music from my PC. I couldn't tell where it was coming from.
Then I downloaded the beta of the desktop WP sync app. This is basically like Zune, but fast and all done in lists instead of thumbnails. I still could not find way to get rid of track listings off the phone though.
Then I found an option in the phone's music and video settings to disable the Xbox cloud collection, and that was the solution.
Now the phone only shows tracks that are actually on the phone. I can find, stream and download (or purchase) music from the music store directly on the phone, and those tracks are also synced back to the PC... success.
I have since re-enabled the cloud sync option in the Win8 app so that all my music is matched and in the cloud, and this lets me access it on the phone or any other device at any time if I really want it.
It was a minor drama to figure it all out, but the result is exactly what I wanted. It keeps the phone clean and lets me have pretty much anything at any time in one place, and without any 3rd party apps or hacks.
FYI, here's the desktop sync app. It isn't necessary, but former Zune users might find it handy.
The Metro sync app has similar functionality, but is more visual and not as fast to use as a result.