This problem had me scratching my head, I had a Logitech G35 headset plugged into my laptop running Ubuntu, and the volume was so low I could barely hear music..
After some searching online I stumbled across a way to use alsamixer from the command line and change the sound card, once I did that I was given some sliders to change and was able to finally get the volume upped to a decent level.
Instructions
1) open a terminal
2) run `alsamixer`
3) once inside alsamixer, hit f6
4) Change to desired sound card.
5) Adjust volume slider to the level that suits you.
Hope this helps anyone else with the same problem.