I don't know about jriver. Roon puts your current music files in a nicely organized catalog, then combines it with what's available in your subscriptions. For example, I have a very large collection of old mp3s that I ripped from CDs years ago. If I search on rune for an album which I have in mp3 format, it will show that album and any versions that are available on qobuz since I am a subscriber to qobuz. For example attached is what I get when I search for U2 unforgettable fire. If I search for something that I don't have an mp3 for, it will only show the qobuz versions.
Oh, and making this screenshot reminds me of the other great thing about roon, which is that it turns your phone into a remote control.