Headset Confusion?

I bought a turtle beach cable to use my x31 on my pc. I managed to finaly get the mic to work but the sound  quality is less then that of the wirlress one I bought the cord to replace. Im not sure if its the 3 different levels it go's through or faulty cord.  Any suggestions?

I allso have 3 audio jacks. Anyone have a clue what the third could be for?

'Info
http://www.turtlebeach.com/products/xbox-gaming-headsets/ear-force-x31.aspx
http://store.turtlebeach.com/ps3pcchatadaptercable-cab.aspx
http://www.newegg.com/Product/Product.aspx?Item=N82E16834220715
Gracias

Make sure you have it plugged into the correct jacks. Without the Amigo II USB soundcard, you should plug into the Headphone (green, rear jack) and Microphone (pink, front jack) jacks. The other jack is a Line-In jack (middle jack) and you should not use it in this instance. Line in needs a much higher level in order to work/sound right. After that, you need to set the levels/boost in your Volume Control for the mic.

Qa