GPL doesn't support EAX - if you force EAX outside of the game you are just basically applying EAX reverberation effects to your entire audio output.
When a game supports EAX, zones are mapped out within the levels with EAX reverb profiles attached to those zones, so when you walk into those zones, the specified profile plays.
For 3D sound on Windows versions after XP, i am pretty sure that GPL uses DirectSound 3D which was taken out of later Windows versions.
You can try this software which works as a wrapper to wrap it to XAudio2:
In terms of hearing where cars are around you, using can use any HRTF with headphones. There are programs for this. There are some free ones that work with any soundchip, like Razer Surround: http://www.razerzone.com/surround
or if you have a creative card, enable CMSS-3D for this.
There were some other free ones, but sadly i can't remember them atm. I'm not sure if Razer Surround is for DirectSound 3D or OpenAL - i've never used it myself.
There is also OpenAL soft for OpenAL games. http://kcat.stranges...net/openal.html
For CMS-3D at least (and maybe other hrtf software), in older games, you would tell Windows / the game that you have a 5.1 or 7.1 system and then let the hrtf software process that into binaural audio for your headphones. Other games don't require this and work properly leaving windows set to headphones (/ headphones).
To be honest, I'm not sure how stereo sound effects help in regards to 3d sound. I imagine they would just be downmixed to mono before being remixed to binaural (hrtf).
Edited by one2fwee, Jul 09 2016 - 06:17 PM.