I have a really good set of headphones. They're only a little over a year old. They are those Sony ones that clip on your ears. They sound excellent and have good bass with my Discman. However, now I have them plugged into the speaker output on the back of my computer. I'm listening to mp3s and they sound like crap. It's almost like the "old record player sound" with very little bass. Do I have a setting wrong or what?