One of the benefits to running a digital signal processor is the flexibility that is afforded for future software upgrades. Almost immediately we noticed that the "processing power" of the Crystal 4630 (at 420MIPS) is significantly less than the EMU10K1 (at 1000MIPS) or even the hardwired Vortex2 (at 600MIPS). Having said that, it is also important to note that MIPS are theoretical, and somewhat vague, so it is hard to be sure that EMU's brainchild is more flexible for real-world processing.

Of course, the most noticeable feature and main selling point of the Game Theater XP is the external rack. Connected to the sound card through a 44-pin cable, the external rack provides all of the functionality one would expect to find on the back plate of any mainstream sound card, plus capabilities traditionally limited to very high-end solutions. For instance, those with Minidisk players will enjoy being able to connect to the optical output while simultaneously enjoying the convenience of the coaxial S/PDIF digital output for a Dolby Digital decoder. Having both digital ports available for input as well is an added bonus, though a little less useful to most of us. Similarly, we found it very convenient to use the Game Theater's external rack to interface a Rio 500 MP3 player rather than fumbling around behind the computer each time we wanted to take our tunes to the road.

The front of the rack provides independent headphone and microphone controls with adjustable gain knobs. Line inputs are also furnished in addition to added USB connectivity and a 15-pin game port for those who haven't yet made the switch to USB-based joysticks.

We only have a couple of complaints about the external rack. First, in order to offer such an expansive level of functionality and to ensure proper shielding, the cable connecting the PC and the rack turned out to be fairly large and not particularly flexible. As such, the excess cable protruding from the rack might inconvenience those who plan on keeping the external rack in near proximity to the PC. Secondly, the presence of the rack itself may be a headache for those with space constraints near the PC. On a personal level, the rack was a blessing for me as it allowed the mess of wiring at the back of the computer to be dispersed across a couple feet of equipment. We can empathize with those who prefer to keep their "rat's nests" out of sight and out of mind.

Physically, the Game Theater XP is a simple board. Since the connectivity options have been moved to an external device, much of the circuitry has also been relocated. Fundamental components, such as the multi-channel audio codecs are maintained on the board, which brings us to our next observation.

Since the latest generation of sound cards has made six-channel audio a possibility, manufacturers have had to depart from designs utilizing a single audio codec, and have begun to incorporate two. Usually, there is a four-channel codec accompanied by a two-channel part for a total of six channels. Interestingly enough, the Game Theater XP uses dual CS4294 codecs - each of which support four channels. My colleague from FiringSquad, Alan Dang, astutely pointed out that this implementation opens the door for some interesting possibilities - should a software DVD player ever decode any of the 7.1 channel surround sound standards, the Game Theater will be able to output the correct number of channels. For the time being, one of the extra channels is used to provide the independent volume control for the headphone output on the front of the rack.