Can soundcard audio range "go bad"?

Is it possible for a soundcard's ability to play certain audio ranges to "go bad"?

I've had an SB Live! in my system for a while, as in maybe five years or so. It's always worked like a champ and I never needed any of the fancy surround sound stuff, so I've been happy with it. About a year or so ago, I noticed that bass levels were sounding pretty bad: as in, the bass in songs started sounding crackly. Imagine if you "blow out" the speakers in your car, that's sort of what it's like. Because of that comparison, I thought my speakers were going bad but it wasn't until now that I started looking into replacements.

As a test, though, I hooked my headphones up to the audio out on my soundcard and heard the same crackly/broken bass effect from them. This makes me think that it might not be my speakers at all, but rather that something on the soundcard has gone bad and can no longer handle the lower sound ranges. Is somthing like that possible? Can a souncard lose the ability to play lower ranges?

Basically, I need to figure out whether it's the speakers or soundcard that needs replacing.

m19