I think you can set up 3 channel using most avrs by just specifying that you do not have rear speakers in the setup. You will need to provide a digital signal to the receiver unless your avr digitizes analog signals. You can use Dolby Digital, NEO, EARS (NAD) to generate the center channel. DD lets you adjust the amount that goes to the center. With HDMI CD/Blu-Ray players, this is pretty easy. With computer music, you can just send the digital signal to the avr. At a higher end, Meridian is very good. They used to have a huge center speaker available for this. Not sure if they still do or not.
In the demo, now did they generate the center channel?
In the demo, now did they generate the center channel?