Yes, you have to have a receiver. You don't have a theater setup without a receiver. What do you mean by another receiver? You need one Dolby Digital/DTS capable receiver if you want surround sound. If your soundcard has digital out, be it coax or tos you should be able to get surround. Obviously, the receiver needs to have the connectors as well. You can also go the analog route as mentioned above and find a receiver with 5 channel input.