I've only just noticed this this evening. I'm playing un-patched Neverwinter Nights 2 on the QX9650 PC (terrible performance) with a Creative X-Fi card. EAX 3.0 is selected in the game settings. The PC is hooked up to a receiver, 5.1 system via optical.

When the PC boots I have 5.1 audio and I can test individual speakers successfully in the Creative Audio Launcher or whatever it's called.

When I launch NWN2, the PC drops back to 2.0 sound. Alt-tabbing to the desktop, re-selecting 5.1 speakers and then alt-tabbing back to the game fixes the issue. I believe this was working without issue before this evening. I also don’t think EAX is working.

Oddly, the ini file in the game install folder has the following settings for Sound:

[Sound Options]
Music Volume=0.85
Voice Volume=0.85
SoundFX Volume=0.85
Music Multiplier=0.60
Dialog2d Multiplier=0.80
DisableSound=0
;3D Provider=RAD Game Tools RSX 3D Audio
3D Provider=Miles Fast 2D Positional Audio
Environment Effects=0
Number 2D Voices=16
Number 3D Voices=16
2D3D Bias=1.70
Speaker Type=0
MaxCachedSounds=100

There are a number of things that look a bit off here. I'm wondering if the game isn't able to update the ini file.