SMPlayer proves my preamp delivers terrific quality!

[gilpel at altern.org]

I said earlier I was wondering what quality of sound I could expect from
the preamp on my mobo. Well, I watched a movie yesterday and used
SMPlayer. Gee, after setting the sound, max volume, enhanced stereo, and
surround sound -- yes with headphones! -- I really had the impression of
standing right in the middle of the scene. I could have turned the volume
so high my eardrums would have blown out! So, the preamp is not the
problem.

Where do I make these adjustments for general use, when I'm listening to
Flash or WMV, for instance?