But my own listening tests have convinced me that discrete recordings can sound better.
Very often if we take a commercial 5.1 channel recording and convert it to stereo using
our 5 to 2 encoder, and then play it back through our 2 to 7 decoder, the result is superior
to the original discrete recording. This need not be the case. There are a lot of sound
mixers out there who refuse to use the center channel for anything, and who’s idea of
how to use the rear channels is pretty primitive. Perhaps they listen only in the sweet
spot! Passing the sound through the matrix system actually improves it. But I have also
heard mixes (and made mixes) where the discrete version is noticeably better – and this is
what I would expect.

Link: side 11

Et gullkorn til:
Ironically, a good 2 to 5 matrix decoder achieves both of these goals from
standard two channel material, and often sounds better than a poorly done discrete mix.