I'm using the M-Audio Delta 410. It provides distinct, physical lines (channels) out to each speaker.

[EDIT]
DSE pointed out in June of 2004: "BTW, while the Revolution does somewhat work for surround authoring, it was designed for surround listening, not authoring."

You can get one here for $150.00 (free shipping).

I'm afraid you aren't going to be able to do what you want using the speaker system you have if they will really only accept a digital (encoded) input.

Here's why: In order to transfer the 6 (5.1) sound channels over an S/P-DIF connection (optical or RCA) the data must be compressed and encoded into a single datastream using one of the standard methods for doing this, usually Dolby Digital (AC3) or DTS. The datastream is then decoded at the far end of the digital connection (the speaker system control box) and the separated signals are amplified and sent to the speaker units.

This is just fine for playing DVDs, etc, since the surround audio on the DVD is already encoded into an AC3 datastream. The DVD playing application merely routes the encoded data to the digital output of the soundcard (adding a flag to indicate to the receiver that it is an encoded signal rather than raw digital audio). And the digital interface can also be used just fine for stereo audio with applications like Vegas.

But when it comes to 5.1 audio with Vegas (or any other multi-track audio app) you run into a problem - the audio you are producing is 6 streams of unencoded data and to pass these all via the S/P-DIFconnection would require them to be compressed/encoded in real time, something that Vegas (or any of its competitors) cannot do. The only way to monitor surround audio while mixing in Vegas (or any other multi-track audio app) is to feed the multiple audio streams to the amp/speaker system as separate uncompressed signals. This could be done as a number of digital connections, but in practice is usually done as a number of analog connections - typically for 5.1 there would be 3 stereo connections carrying: Front Left, Front Right; Rear Left, Rear Right; Centre, LFE. This requires the sort of multichannel audio interface that you have been seeing referrences to from M-Audio and Echo (I use a RME HDSP Multiface myself) which provide a number of separate audio outputs, usually in groups of 8 rather than just the 6 you need for 5.1 audio. And I'm afraid these just aren't available for $100 even if you could use them with your existing speaker system which you can't.

I'm afraid that the bottom line is that in order to monitor/mix 5.1 sound in Vegas you are going to have to buy (1) a soundcard that provides multiple audio outputs and (2) an amplifier/speaker system that can accept separate audio inputs for the 5.1 audio signals from the soundcard.

I don't believe you are going to be able to get anyhere near this for $100. There is a possible cheap way of doing without the soundcard part of this, though. You don't say what motherboard you are using, but if it has a digital output than there is a good chance that it also provides 6-channel (5.1) audio on three 1/8" mini-jacks. If so then you can use these outputs to route the FL/FR, RL/RR, and C/LFE pairs to your amp/speakers - the quality won't be that great but it will provide a usable signal. Then you would just need to provide an amp/speaker system with separate 6-channel inputs. If you are lucky you may be able to use your existing speakers and just replace the amp with a suitable Audio/Visual (AV) (multichannel) device. You may be able to pick up something cheap on Ebay. (I use a mid-price Yamaha amp, a DSP-AX630SE which is fine but has a lot of bells and whistles that you never actually use - one of the cheaper Yamaha AV amps without any of the clever stuff would do fine just so long as it has the 6-channel inputs.)

Mark

EDIT: Oops, as the other posters have pointed out it is possible to find a multichannel audio card for under $100 - the M-Audio Revolution 5.1 - so I was wrong in my assertion above. Nevertheless, you will still need an amp/speaker system which will accept the three pairs of analog outputs, i.e. one with 6-channel inputs, just as you would if you were using the 6-channel analog outputs that may perhaps already be provided by your motherboard (if you are lucky).

There are lots of sound cards that offer surround audio outputs and also SPDIF in/out. I may be missing something here, but for example I use a Turtle Beach Santa Cruz sound card to drive my surround speakers via analog speakerout lines. Turtle Beach offers cards from $30 to over $100.

I chose the Santa Cruz card last year (now discontinued) over other inexpensive sound cards because the software included a equalizer. I've done a half-dozen documentary projects in Vegas using surround audio and encoded ultimately to DolbyDigital 2/2 surround sound on DVDs, and they turned out great.

I use the Terratec Aureon 7.1 Universe, and 5.1 from Vegas is fine from this card - even in the preview. Even if I think, that this card is more expensive then $100.

For a great moderately priced solution I have the M-AUDI firewire-410. Love it.

And as Mark says you will then need to go from the sound card to your surround sound processor amp and then on to the speakers, or as is often done in pro studios, get powered speakers and miss the amp stage. I use a Yamaha RX4100 series, excellent audio in a bottom range price.

An alternative, now that stereo is dying and there are many stereo amps around for pennies, get three used stereo amps. One for the main, one for the surround, and one for the center and LFE. I have a second system like this using old NAD 7600's that are fed by the Firewire410 and it's killer!

why not just get a surround sound system that supports seperate speaker inputs? I use onboard audio & a RCA 2280 reciever. Works like a dream. :)

So just to be clear: As far as anyone is aware there is NO $100 audio card that can go out from Vegas through the S/PDIF and into powered surround speakers? (In other words, NOT go out from separate 1/8th inch mini plugs.)

BusterKeaton you mentioned the M Audio 5.1 card. Will that really go out from the S/PDIF coax and let me hear surround from within Vegas?

Fred

As I attempted to explain in my previous reply, to send multichannel audio via the S/P-DIF requires it to be compressed/encoded to a single datastream using something like AC3 or DTS. To use a setup like this for mixing/monitoring surround audio with Vegas would require the six audio channels to be encoded to AC3 "on the fly" and Vegas cannot do this (and nor can any of its competitors as far as I know).

This means that (for mixing/monitoring surround audio in Vegas) you need to feed the audio to the amp/speaker system via separate uncompressed connections, usually three stereo pairs - you cannot use a single S/P-DIF connection for this purpose. (You can use the S/P-DIF connection for surround audio that is already encoded to AC3, for example from a DVD or a a game, but not for audio that is not already encoded to AC3, such as that coming from a Vegas surround mixing session.)

To explicitly answer your question: There is no card (either above or below $100) that can allow you to use the single S/P-DIF connection for surround mixing/monitoring in Vegas. Any soundcard must use separate uncompressed (usually analog) connections for this purpose. And to hear the surround audio from Vegas you are going to need an amp/speaker system which can accept these separate multichannel inputs.

Mark

To explicitly answer your question: There is no card (either above or below $100) that can allow you to use the single S/P-DIF connection for surround mixing/monitoring in Vegas. Any soundcard must use separate uncompressed (usually analog) connections for this purpose. And to hear the surround audio from Vegas you are going to need an amp/speaker system which can accept these separate multichannel inputs.

Well said, Mark. This is why I simply suggested the M-Audio Delta 410 card and the M-Audio LX4 5.1 system. They work perfectly together, they sound great, and they don't break the bank!

Thanks Mark and everyone. I think what I'll do is just exchange the speakers for a set that has separate mini plugs. It's just a shame because these really are great speakers. Oh well.

Cheers,
Fred

the speakers should just be wire, unless they have a build in amp & that needs a coax/SPDIF interface.

If the speakers are seperate from the amp, just get a different amp that supports what you want. I lucked out when I got mine... radio shack had them on sale ~5 years ago. I can't get anything with simular capabilities for that price there anymore. :)

Speakers with mini plugs? Speakers that are good enough to be able to use as a studio monitor for Vegas have great big heavy thick gold plated posts don't they?