You can Have 5.1 analog sound out for gaming and movies.
First off... there are several people who need to go pick up some audio technology books and do some reading. Terminology in audio forums is greatly misunderstood.
Ok, I have a Mac Pro rev2, 17"MBP rev2, 15MBP rev1.2 and have been digging into the Audio abilities for quite awhile. Here are a list of Audio Devices that I have purchased and confirmed work with OS X with 5.1 Surround Sound out:
1. Griffin Firewave (Discontinued):
http://www.griffintechnology.com/products/firewave
2. Creative X-Fi USB
http://www.soundblaster.com/products/product.asp?category=1&subcategory=873&product=17751&listby=
3. Miglia Harmony Audio (Discontinued) [supports 7.1]:
http://www.miglia.com/products/audio/harmonyaudio/index.html
In OS X Leopard, all these devices have to be configured properly in the "Audio Midi Setup.app"
For gaming support, Its a hit or miss based on the company doing the programming. OpenAL has a few different versions and unfortunately many programmers have been ill trained in the Microsoft world and don't know how to implement properly but that is changing...lol.
OK I play WOW and the surround sound when Playing on any of my MACs with any of the above external sounds cards, is second to none. I've had guild mates over who are windows only people and they have gone "wow!!!" over the Surround Sound as it sounds better then their setups with 5.1, 6.1 and 7.1]. I've had success in a few other games with surround sound, but until programmers fully learn the OpenAL standard, we are in for allot of C R A P!
If you pickup a one of these devices and cannot figure out how to configure it (and there are no drivers to install) drop me a line at " z 1 r o s s @ g m a i l . c o m"
Here are some issus:
1. There is no Dolby digital Live support.
2. Leopards DVD Player only decodes 2ch DPL sound, have to use VLC Media Player
3. Must have Surround sound speakers with 3 analog connections for Front, Rear, and Center/Sub.
4. Griffin Optical pass-through is tricky to get working for movies.
5. (In OS X) the X-Fi USB volume dial doesn't work and volume control is entirely up to your speakers as it only outputs one preset level.
Now the X-Fi USB is the best on my Mac Pro as when I bootcamp into Vista for gaming, Its got full driver support and everything works perfectly.