Sound card to couple with a Marantz SR4500

Hey guys. I want surround sound on movies and games from my computer. I have a Marantz SR4500 AV receiver with an optical input jack. I'd like to pass unprocessed multichannel signals upto 94Khz to my reciever from my computer, using an optical output. I don't want to pay too much, as all I really need is the output jack, no downmixing. Please advise.

Marantz is a super excelent brand, and you might paid incredible amounts of money so don't be greed.

On the other hand, here's the picture for optical audio:

SPDIF supports up to 24/96 I guess. But just 2 channels.

For 5.1 what you need is Firewire (non-optical) or ADAT mode (from Tascam I guess) if your AV supports it, the Intel HD mobos have it. It's just like SPDIF but with more frequency (in the end, data-rate).

Will pump 5.1 but it's not much supported.

On the other hand I have just seen that there are DTS live encoding cards that will convert 5.1 to DTS which will go trhough SPDIF fine, and it's 1.5mbps and discrete channel will give you good quality (if the encoder is good). http://www.bluegears.com

AC3 is not Discrete Channel... it has 2 channels (stereo) and use Matrixing to add channels (phase change that can be used to discriminate channels)

DTS instead is like having 5 wavs (or 6, I can't recall if low freq is pass through alow pass filter or is an independent channel)

Yes he can choose the cheapest sound card since Surround would be decoded on his receiver if it's possible to do so. All you need is optical TOSLINK. If you need Coaxial SPDIF be aware some cards have bad signal and the receiver will not be able to decently decode (sound will stop when bad data is received)

Does the Chaintech card output a "bit-perfect" Sp/dif output or is it resampled?? Youll never get good sound quality from an output like the Sp/dif outputs on most mobo's because the signal is resampled. You need something with a bit-perfect output to get the best sound quality.