Uhm, what's your price range haha. If you want to avoid a receiver you will have to go with a power amp and have your sound card be the pre-amp/processor.
Could you also let me know what speakers and sound card you are using.
You can always hunt audiogon, kijiji, etc for a used power amp but you probably won't find anything for a better price than a new Emotiva UPA-5 (currently on sale). I have their UPA-7 and UMC-1 which are amazing.
UPA-500 Five-Channel Power Amplifier | Emotiva Audio | High-end audio components for audiophiles and videophiles, spanning 2-channel music systems, as well as 5.1 and 7.1 home theaters. Products include multichannel amplifiers, stereo amplifiers, and
Edit: Also, unless your satellites are powered...there is no way a sound card will be able to provide enough juice to them.