I play less then when I was younger and had more time but at least now I can afford proper equipment

I upgraded my Audigy 2 ZS to X-Fi and it sounds defenitely better, less cluttered. This is audible in games but also when playing stereo music on mu 5.1.there is audible difference. I guess CMSS has been worked on and improved.
Sound in Quake 4 (EAX5) and FEAR (EAX4) simply scares, it is sooo acoustically accurate it scares. I like EAX, It used to be just reverbs with Live cards, but it went a good few steps forward. Creative included Aureal's technology in their original EAX 1 and 2 that is de facto sound gaming minimum now, as it is supported in software by almost any soundcard because it was opened to public in 1999 I think. But EAX 3, 4 and latest 5 with Sensaura's Macro FX and 128 voice support still work only with Soundblasters Audigy and X-Fi.
It's due to our hearing that is quite forgiving about sounds missing so you do not actually realize things could sound better until you listen to them sounding actually better. It is not like with graphics where differences are obvious and easy to perceive. Hearing differences in sound is a skill people are losing.