I plugged them into the back of my computer and they are really quiet. I have a crappy sound card I bet, but I just want to play music. I can take the left out from my right speaker and put my headphones in, but then I only get sound from the left side. It doesnt distort when I turn the volume way up, but I want it to be louder with sound from both sides. I have all settings to the highest volume on the computer too.
The line out of your computer was never meant to drive headphones, it doesn't have enough juice. What you need to do is buy or build an amp and run that line out signal in to it, and then plug your headphones in to an amp.