Because it was determined a long time ago that reviewing and bench marking sound cards was a major waste of time as they all perform almost identical on pretty much all feature sets.
Final Verdict: Built in sound comes on most motherboards and is generally as good as any add on card.
I have to disagree with you on that. I still have my X-fi Xtreme Music installed and the sound quality is on a whole other level compared to integrated audio, which is dominated by Realtek as far as I know. The difference is way to obvious not to notice it. I don't mean to be rude but do you really have a dedicated sound card which is inferior or the same as integrated sound? If so, I would like to know models and brands.
I do however find it a bit shameful that EAX has no support whatsoever in games. I think Creative screwed up big time on that, since EAX really does make a difference in every game that I have used it on that supports it.
Still, I would like to know why Tom's Hardware hasn't done a sound card reviews in a while.
I honestly doubt sound has improved much since the X-fi cards but I still believe that this site needs sound card reviews.
though this thread is a few months old, i don't really see a response that addresses the issue put forth so i will pipe in.
mostly i think it has to do with consumer demographics/market share. i'm a gamer and an audiophile. as such, i believe that there a few things at play here:
1) audiophiles are already a VERY niche (ie very small) market. they also tend to be somewhat technically inclined (at least most of the ones i know). as such, they understand that for various technical reasons, computers and true hi-fi do not mix very well. you could, of course dispute this (and there are some exceptions with VERY specialized equipment) but for the most part it's true. so... niche market + highly specialized gear = too small a consumer demographic to really make it worth addressing.
2) most gamers don't really care about the kind of nuances that differentiate various sound cards and integrated audio -- at least not anymore (mostly due to advancements in integrated audio). sure, they might be able to hear the difference, but is it really enough to significantly alter game play immersion? again, an argument COULD be made that it is... but the difference between using an expensive sound card vs integrated audio is NOT likely to significantly alter your experience of... say... farcry 3 or borderlands 2 or (insert your favorite modern game here). and this issue is only further compounded by the fact that a great sound card is still limited by the hardware feeding your ears (headphones or speakers/amplifier and cable).
3) not only that, actual benchmarks for sound cards do not yield the kind of tangible numerical differences you get with other hardware benchmarks. i mean sure, you could look at signal to noise ratios or THD (total harmonic distortion), etc; but even those numbers aren't going be as noticeable as, say, the difference between 50fps and 60fps you might get from comparing graphics cards. and again you run into the issue of headphones or speakers/amplifier and cable characteristics.
in short... sound tends to be relegated to the realm of "good enough". if it's good enough then... well... it's good enough. and the people who would might be inclined to differentiate between "good enough" and great are simply too small a group to make it worth the time and energy it takes to perform and publish such tests. in which case a quick google search will probably be enough to land you on a site that caters to more "niche populations".
i hope that explanation helps. please feel free to flame me if it doesn't.