Right now, you can only play music that’s in your library. We could conceivably offer some kind of “preview” mode where tracks could be queued up without being imported, but it’s not as simple as you might be thinking.
For example, let’s say my laptop is running as a remote – my Roon Core is running on the other side of the house. If I drag and drop a song into Roon, it could potentially be added to the queue without it being imported, but what if I then sleep my laptop? If the file wasn’t added to my library, how does my Core access the file to continue playback?
What if someone else in my home hears the song playing and wants to add it to a playlist? The song isn’t actually going to be available once it finishes playing, since I never imported it to my library.
There are a huge number of little cases like this we’d need to consider, and almost all of them require some version of copying the file over to the Core, even temporarily. We haven’t received a lot of requests in this area, but feel free to make a thread in #feature-requests describing what you’re looking for.
Thanks!