[erik_p]

It can do a pretty impressive job, it does help to use high quality source material. Using mp3 rips from youtube might get a little more artifact-y. sometimes, vocal like instruments will get pulled into the vocal rip instead of the "karaoke" instrument part of the extract.

[superfamicom]

An interesting side effect I've seen with FLAC vinyl rips is an interesting type of noise removal on the "karaoke" tracks.