Something's not right here.

"Mic output" --> Why are you using a MICROPHONE and what is it coming OUT of? Think about which directions the audio is traveling (In or Out), and I take it you're using a line level audio connection into an input designed to accept line level sources?

Secondly, do you know what mono is? Why would you record stereo music in mono?

Lastly, there's something catastrophically wrong with your settings. An hour of stereo music recorded in WAV 16bit/44.1k would be around 600MB, and half that for mono. You've got 2300MB? What file format did you go with? Did you record video at the same time?

As for the original poster, are your levels in the mixer still looking OK despite switching sources?