I bet you could even feed the raw 16-bit samples into the echo buffer and avoid any artifacts from the BRR compression used for normal samples. You'd set up an identity FIR kernel for the echo feedback and somehow keep track of where the echo pointer is.
Actually EAX 2.0 is an overhyped I3DL2 which is part of DirectSound. The same effects can be achived using the I3DL2 code as the EAX code. The only difference really shows is EAX 3.0 and newer proprietary extensions. EAX 1.0 died getting out of the starting gate.
I have added SPD/IF passthrough support for people with cards that support it for games that support pro-logic output. I am not sure this effect is retained if you play it through your card's analog outputs I think some DAC's might strip it out. At least I can confirm it works properly on my nforce2 on SPD/IF output. It's quite interesting to play Vortex and ToP with sounds surrounding you.
