I hope this is no longer true, but I asked this question several months ago and the answer was No because it would have to be a part of the drivers. The only EQ's available are built into media players, and I'm assuming that you already know about those. However, your onboard sound drivers that came with the mobo may have this "global EQ" as I call it. But onboard sound sucks, so it's not really worth it.
So, as far as a "global" EQ, I think the only option is to get an actual sound card. I mean, I strongly feel that going with a sound card is just as important as going with a graphics card instead of onboard graphics. Not only that, but using a sound card (and disabling the onboard sound) frees up system resources to possibly help you take your overclock a little further.
But beyond that, the difference in sound quality is just about as big as the difference in onboard graphics vs. a graphics card. The difference can be like night and day, especially if you get a decent or good sound.
But be careful what you get too. Like, don't get the X-Fi Xtreme Audio. It's just a re-branded Audigy SE card. It doesn't have the X-Fi chipset, but rather its chipset is based off the Audigy 2 SE and Sound Blaster Live! 24-bit, and even requires those older drivers (source
). And believe me when I tell you that I had even the Audigy 2 ZS, and the difference between that and the X-Fi chip is definitely noticeable. But then when I compare my sound card to onboard sound, the difference is even more noticeable.
So, if you really want global EQ and you have the budget for it, then I strongly recommend a good sound card. And depending on your budget, you may be able to get something pretty awesome. However, I will say that I feel my X-Fi XtremeGamer (the low-profile card) is pretty awesome. It continues to impress me. And it can be had for $90 or less.Edited by TwoCables - 2/4/09 at 2:55am