i was looking at terratec sound cards yesterday and i was eventually directed to an actual amplifier for your pc and it uses an expansion slot in the rear of the pc....duh..... and cost about 200 smackeroos. it has an ..ok...power supply giving your pc direct 20 watts per channel to regular unpowered speakers. it works with your pc's sound card, and is not a sound card , but rather an amp for your pc.
i imagine if your pc has enough slots in the back, you can probably run 2 of these for 4 speaker setups, and use the sub-woofer output on your sound card for a powered sub-woofer.
either way , i can't justify 200 dollars for a mere 20 watts per channel...stereo only...., and to top it off...i imagine any decent amp would throw unwanted heat into your already warm pc.
if you already have the speakers, go buy an inexpensive surround receiver . i would guess a 100 watt per channel receiver would sound better than a 20 watt amp in a pc anyway
if the pc amp thing was 20 dollars each, i still would not go that route because of the heat in the pc.....they are about 200 each....eeewwwwww.......
if you are into pc's or know anyone who is, and i mean someone who really knows about pc's.........they will tell you a pc's worst enemy is heat....hmmmmm, i think that holds true with most things.....he he he
if you want any kind of quality sound from a pc, don't start building up some lame-ass , slow crap. make sure your pc is resourceful enough. none of those 400, 500, 600 mhz systems........
either way, good luck, and i hope i was helpful
ps...i'm smarter than einstein.....he he he