I use a 5.1 system and tailored my steretool settings specifically for it.
viewtopic.php?f=10&t=2764
I don't suggest using software matrix decoders/encoders or any thing that says "virtual surround". Your receiver should have something similar built in that works a lot better and has hardware optimized for that function!
On my panasonic receiver I have 3 Dolby Prologic settings, Movie, Music and Panorama.
When I'm looking for "surround" effects I go with Music mode. Which balances out the equalizer too so the highs are too saturated but the bass still kicks!

Movie mode centers the stereo too much so I don't use it at all.
Pano I like when I want to show off cause it widens the stereo and makes everything sound like a theater.
When I want the loudest sound I click a little button called "Surround mode", it pushes the amps in the receiver to their max. All the speakers output the same audio, except for stereo differences and the center speaker stays as a really loud tweeter. I love this setting cause its as loud as my system can go.
Finally I use stereo when I'm looking for close to bit perfect sound recreation. This is mainly for editing, and settings work.
Also upgrade to flacs if you can, those are awesome
