Actually, thinking about it- That seems to be pretty likely.
I've found my system (I also have a Creative Audio card) will reset the Speakers to 7.1 after a driver update and it causes very odd audio effects and sounding "far away" is one way I'd describe them. In fact, I was going to post recommendations of that sort but the way mine is setup I leave my headphones plugged in all the time and switch to it with the control panel, so in my mind I was thinking that headphone output wasn't possible with 7.1 enabled. But of course that isn't the case- It's just how I'm using it. I could just as easily plug my headphones into my headphone jack directly with an adapter (it's a large TRS connector which the breakout module supports) , at which point 5.1 or 7.1 or whatever will be "active" with the headphones, rather than the dedicated headphones mode.