http://www.cirlinca.com/highresolution.htm

Get more from your music collection. Import music tracks from computer 
files or CD. If they are in stereo, convert them to surround 5.1 for an 
immersive experience. And/or upsample them to high-definition up to 
24bit/192kHz for enhanced clarity and details. Export to DVD, Blu-ray or 
files.

When your music is not already in high-definition or surround (e.g. it 
is of CD quality), you will benefit to remaster it (i.e. process and/or 
convert) :

To encode the audio signal in a way that is more easily reproducible by 
electronics equipment with less distorsion and closer to the original 
analog signal with a technique called upsampling.

To supplement the stereo reproduction with surround channels to restore 
the sound stage to something closer to reality with a technique called 
upmixing. The front stereo channels can be left unchanged.

The result is a superior listening experience having more definition, 
clarity and presence, that has been qualified as "more fluid, less harsh 
and an all round better sound".