The PCDJ software loads slow, has the jittery feel of programs ported over from Windows 3.1, and is unlikely to win any awards for interface design. That said, this is the rare piece of software that’s both free and priceless.
What it does is allow you to play any two MP3 files simultaneously (even the same file, with no need to make duplicate copies), and to set the tracks’ volume levels separately, a la a real-world mixer.
For fun, make an MP3 of something extended and minimal — say, an instrumental movement from a Philip Glass composition. Then play the file against itself, starting the second copy a bar or two later than the first, sort of like a round: it’s a poor man’s dub minimalism, and it’s addictive. Check out the gratis program at the VisioSonic site, visiosonic.com.