Below is a non-exhaustive, probably U.S.-centric list of sources for licensed MP3+G or MP4 files (additions welcome):
Karaoke tracks require original recording and production. Please support the creators!
No, but… is it still karaoke without a mic? :)
Karaoke Forever makes no assumptions about audio input so that it can work with any microphone setup, including none at all. The player’s output (music) can be mixed with microphones in software or an outboard mixer (see below).
There are generally 2 ways to mix Karaoke Forever’s player output (the music) with microphones. In either case, at least 2 mics are recommended.