Is there an app like this? (sync service)

I want my music folders to be the same on my pc and on my android device. I mean syncing the two folders through wifi, when available, i want this app to make a "folder-pair" between my android and pc. I tried Dropbox, Box.com, Sugarsync and many other apps, but non of them were good, because they keep the files in the cloud, so it's not available for offline use, or the other typical problem is that theese apps requires, that the android device and the win pc must be connected to the same (home) wifi network. I have about 10gigs of music, and I want at least 5gigs of these to be synchronized. Any solution or app suggestion?

thanks a lot

Hmmmmm...good question. Doesn't Spotify allow you to cache songs for offline listening?

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I live in Hungary, and Spotify is currently not available here.