How can I connect 5.1 surround sound speakers to my Mac Pro?

As far as I know, the only way to do that is with the digital out, toslink I believe(1). . Currently there are very few external usb soundcards that are known to work with Mac and produce 5.1 sound, perhaps Diamond Multimedia or Zalman?. Analog surround really doesn't work (green, yellow, black cords)*. So, maybe, Garage band/VLC? or the dvd player might be the only things I know that could produce 5.1 sound, but I could be wrong.......

(1) You will need a speaker set with an optical input...

* maybe try this--i think it's called an " HD audio rush " box and it converts digital to analog audio 5.1 supposedly-, you can look on ebay for similar things

sorry I couldn't be of more help

John B

The only port i know for speakers is the headphones port