Need Help with external sound card!

I have a msi z77 e53 mini itx mobo, the problem is that my microphone ( mod mic 4.0)  is too quiet at base levels and as I boost the microphone it makes the hissing, which is already present worst. The output audio is not optimal for my denon AH-d1100. I am looking for an external USB soundcard with good input microphone audio and good output audio with as little hissing as possible. My price range is below $100 I am situated in canada. I don't need anything that is audiophile grade just something better than my mobo audio I cant afford anything over $100 as iI am a poor student. I need a USB sound card because i don't have any pci slots. I am here because i dont know where or how to start.

Thank you,

Is the mobo's audio realtek?

Go to the Realtek HD Audio Manager from the Control Panel then click on the Advanced settings in the upper right corner. Chose separate inputs. Then check to see if the problem follows when moving to the back mic jack.