These profiles include a set of performance tweaks that act on some system kernel parameters. It does not have anything to do with DSPs or other sound effects: the output is kept untouched (bit perfect). It happens that these parameters introduce an audible impact on the overall sound quality, acting on kernel latency parameters (and probably on the amount of overall jitter). Sound results may vary depending on where music is listened, so choose according to your personal taste. (If you can't hear any tangible differences... nevermind, just stick to the default settings.)
Just some handy system commands, without the hassle of logging into SSH.
For people suffering problems with some receivers and DACs.