Sound issues aren't too uncommon with the Forte, but some are easily solved and the card is pretty good for what it is, so you might want to check around in this forum and on the web. I was having problems with static and strange hums, and it was solved by putting electrical tape on the metal tab of the card so it was somewhat insulated from my aluminum case.
Have you been able to do some basic troubleshooting? Like have you tried using a different set of headphones (you said they're new, but maybe they're too sensitive or the cord is picking up something), or reseating the card, or using another slot (if you have a spare)?