Optical Input on Creative Labs Sound Blaster X-Fi Xtreme Audio PCI-E with Logitech z-5

Question

So i plugged in my Optical cord into my new sound card the Creative Labs Sound Blaster X-Fi Xtreme Audio PCI-E and it worked only in the Front right, Front left, Front centre, and the subwoofer. Now i hear i need a external decoder... but then again that my sound card should decode it as well... the place i bought my card recemended a optical cord for my card?with the?speakers i have?(the?Logitech Z-5500) How much are decoders? What should i do next? Creative seams to have limited support especialy on optical inputs.

Answer 1

I must have answered something like that in another thread sometime ago, but here goes:
A single SPDIF connection, optical or coaxial, will only transfer stereo in analog form; no rear or centre channels!
There are two ways you can get all speakers playing via such a connection:
() Get your speakers to upmix the audio source to play on all fi've of them
(2) Output a Dolby Digital (AC3) or DTS signal. These contain the multichannel information encoded in the stereo signal. A suitable decoder (such as the one contained in the Z-5500) will be able to analyze the signal. Unfortunately, this is something you can mostly find in movies.
So, to sum it up, no natural everyday multichannel sound over one SPDIF (e.g. no EAX, directsound3d etc.)