How to fix a half broken soundcard?

Sounds like the output of the audio card might be messed up or "jarred" a little. Mine does this, but only through the headphone jack, not the balanced speaker output jack. All I have to do to fix it is jostle the headphone input a little and it goes back to normal. What seems to be happening is that the audio phase gets messed up and thus cancels out certain frequencies in the mid-range, like vocals. What you could do is open up your audio interface or remove your sound card and clean the internals with high potency rubbing alcohol. Let it dry and reinstall it, including the drivers if it makes you feel better. If this doesn't work, you may want to re-solder your output connections to the circuit board so that there are clean and solid solder points. Otherwise, it may be time for a new sound card. Good luck!