X-Fi MB(2) software package for integrated audio codecs, for a start. I've tried some modified Realtek drivers in conjunction with X-Fi MB2 on a notebook, but it only got up to EAX 4.0.
The X-Fi Go! Pro also claims to support EAX 5.0, and I highly doubt a little USB stick can pull that off without software audio rendering.
Did not know about that. Good info!
And unfortunately I don't play anything that uses the loftier EAX extensions, and I don't feel like having both installed at once or switching them out, so I can't do much more than say it works (seemingly) as well with what I do play.
My suspicion would be that it's probably a "cut down" version of the X-Fi; in terms of economics it would make sense - take the features that the users want or need, and make it more affordable on both sides. It probably does what the EMU20k can do, but probably doesn't have as much processing power (and is probably a more fixed-function DSP instead off an FPGA (I'm convinced the EMU20k is not a fixed-function chip)). To support this all I have is that Creative isn't making a lot of racket about how they've increased processing power yet again (which was the X-Fi's whole selling point, that it was multiple times more powerful than the Audigy, which was itself more powerful than Live!, and so on). But it might just be that they're changing their marketing strategy as well. Who knows.