Thanks for the reply :-). PCI soundcards can be tricky because more recent chipsets treat PCI as a bit of a stepchild - the newer the chipset the more tricky things tend to get. One phenomenon for example is erratic audio channel jumping - e.g. sound jumping from the left to the right or front to rear (independent of the type of application (e.g. media file, game, etc.)). This does not happen with the PCI Express version of the X-Fi.
However, Chaos Engine Remastered is the only game I have where digital sound effect stuff stops playing altogether (until reloading the programme) - mind you, the music continues to play.
I am not an expert on these matters but I presume that The Chaos Engine is not using the driver for your PCI (not PCI Express) card correctly or there are some severe compatibility issues between the game and the card since, again, it would appear to be using older drivers :) Of course, i am simply theorizing since I don't have your setup directly in front of me :) I am surprised that PCI is still somewhat usable these days, to be honest :)
The drivers are current (on both versions - as are the DirectX versions) and on my i7 it seems to work fine. Otherwise the PCI X-Fi still is lovely - it does even sound a bit more crisp than the PCI Express version I have my proper computer. Apart from that sample rates can be put up to 192KHz while the PCI Express version can 'only' go up to 96KHz. It still is an amazing card (both are) and knocks the socks of any onboard stuff. I was shocked how weak (no, I do not mean hardware 3D sound) the supposedly decent onboard stuff (Realtek) sounded in comparison - and in went my X-Fi immediately :-).
I use the Creative Alchemy stuff with (almost) everything (reviving EAX / Directsound hardware stuff in games / programmes that still support it - even stuff like Fifa 14 that supposedly only has stereo sound suddenly becomes 5.1 - alright, I do not know whether it actually goes 3D sound or whether the front two channels are only mirrored to the back - I don't care it still sounds much better than mere poxy 2.0) - even with older games that 'only' support Directsound hardware mode. The sound quality generally becomes more crisp! Apart from that, I also noticed with my old Audigy under WinXP that games would started a little bit (alright but still noticeable) quicker.
I still find it unfortunate that Microsoft scrapped hardware sound when Windows Vista was released. On my old AthlonXP 2800 (2.0 GHz, Barton core), I was still able to play Half Life 2 or Bioshock at 1280x960 with full(!) detail (ATI Radeon 3850 and 4650 AGP) - thanks to the X-Fi - alright, not with triple-digit frame rates but 40ish was and still is perfectly fine with me. I also did not bother about anti-aliasing (actually I still don't really - in a way it is like with cars: 16 valve four cylinders is nice but proper 8 cylinders still has more punch...). By kicking out hardware sound, Microsoft basically reduced to electronic scrap overnight (!!!) older computers that were otherwise still doing the job swimmingly.
Anyway, thanks for the reply.