The Power Macintosh G5 is the first Mac model to incorporate support for digital optical audio, both in and out.
By definition, optical audio provides a fiber optic digital audio connection used to connect a digital source component (such as a Mac, DVD player, console, etc.) to a receiver or pre-amplifier.
What makes this standard better than analog audio out is that the data passed is the "raw" digital audio signal using laser (light) pulses. Purportedly this interconnect minimizes the interference and degradation.
Microsoft has been using digital optical audio out in its XBox gaming console almost since the unit's debut, requiring the purchase of the "High Definition AV Pack" and a separate optical cable.
Now that Apple's high-end systems are equipped with optical audio out, they can make use of speaker systems like the Logitech Z-680 - currently being offered at the Apple Store - which provides THX-certified "theater quality" digital sound through optical and coaxial inputs.
You might have to apologize in advance to your neighbors for this system. It includes a 188-watt subwoofer, four 62 watts (RMS) each satellites, and a 69-watt center channel. And to boot, the Z-680 comes bundled with a Monster Cable Interlink LightSpeed 100 cord that plugs snugly into the back of your Power Macintosh G5.
While cords produced by Monster Cable certainly hold the highest regard for sound quality and durability, you can pick up an optical audio cable at your local Wal-Mart, Best Buy, and various other outlets.Feedback? Latefirstname.lastname@example.org.