In 2005 I encoded a bunch of stuff using MusicMatch, which I believe used the Fraunhofer encoder.

In any event, it was before I really knew what I was doing, and at the time the default setting was for 128 KBPS "Dual Stereo". Now, I know the difference between Stereo/Joint stereo, but does anyone know if dual stereo is of lesser quality? I did a little bit of research into it, and all I can find is some reference to it being used for dual language audio programs. Is Dual stereo true stereo?

I don't need the technical explanation for what dual stereo is...I know its basically two independent mono channels. My question is, how does it compare quality wise to stereo/joint stereo? There must be a reason it doesnt seem to be commonly used.

Any insight would be great!

The terminology used by different encoders is not always universal, but if by "dual stereo" it means that the two channels are encoded independently, each getting exactly half of the available bits, then depending on the material there could be some loss in quality if, for example, one channel needed a lot more bits for encoding than the other but was no able to get them (sorry for the run-on sentence).

Ordinary stereo is more efficient than dual stereo, and joint stereo is more efficient than ordinary stereo, so that is also the order of increasing quality for cbr files, and the order of decreasing file size for vbr files.