Converting an analogue 5.1 signal into digital. (For Pioneer SE-DIR800C Headphones)

[NinjaHeretic]

My PC has a SoundBlaster Audigy 2 card, which when playing games will output 5.1 sound only through its 3 analogue outputs. My new Pioneer SE-DIR800C surround sound decoder & headphones only accept 5.1 sound via its digital inputs (optical & co-axial). So, how do I convert my soundcard's analogue signal into a digital one? What hardware do I need to purchase? Or would I be better off buyinga different soundcard that will output a full 5.1 digital signal when I'm playing PC games?

I know that as a compromise, I could output stereo sound from my PC and use the decoder box that comes with the headphones to upmix the sound into 5.1 using the inbuilt Pro Logic II or Dolby Headphone technology, but I guess that this wouldn't sound as good as if I could get the real 5.1 signal from my PC into the headphones.

So, back to my question:
What hardware do I need to buy to convert an analogue 5.1 signal (via 6 x RCA or 3 x 3.5mm stereo ) into a true digital signal (via optical or co-axial SP/DIF)? Is it some type of AV Receiver or headphone amplifier I need? Or is there a different soundcard I could use? If possible, please recommend makes & models of equipment.

 

[nghiasays]

I thought all the Audigy cards have a digital(S/PDIF) out and all you need is a cable.

http://www.creative.com/products/pro...uct=4915&nav=2

 

[AdamWill]

nghia: the problem is that digital outputs will only output a surround sound signal as an encoded stream (AC3 or DTS). Movies have their soundtracks encoded like this, but games don't produce surround sound in this way, they usually use the DirectSound API which - as the original author mentioned - only outputs in analog. To the OP, the only way to do what you want to do is to get a soundcard or a software plugin which can encode surround to AC3 on-the-fly. There's a couple of soundcards which do this, I believe, check the computer as source forum or www.hardforum.com. There's also a couple of DirectX plugins, but at least as far as I've heard they're very immature and may only be for media, not games.