Recs.
Updated
TOMAHAWK is a cross platform social music player that plays local music files as well as integrates streaming services.
Specs
Pros
Pro Plays from online third-party sources
You can connect Tomahawk with Spotify, Google Play Music, Last.FM, YouTube, Soundcloud, and a lot of other online sources. This means you have instant access to virtually any song you could ever want - even remixes (especially on YouTube) from this one program.
Cons
Con Lacks some polish
While listening to music, the music area doesn't scroll along with the music. Also, some of the plugins are slow to respond and they each provide a slightly different experience with which information they show, and how they show it (there isn't a standard format).
Con Development seems to have stalled
This project's github readme.md states that the project is abandoned, although some people appear to be contributing still.