|I can't find the recording audio line to record what I hear|
Recently some manufacturers have disabled this audio line being the case for example of Dell's SigmaTel new audio drivers in which you won't find the mixed recording audio line at all. This line does not exist under this audio driver.
Know more about this : http://www.togeo.com/togeo/wordpress/?p=38
All drivers have to make at least these three lines available: line-in and microphone.
For your problem to be solved you will have to connect a P2 cable from Line-Out to Line-In. The specification of the cable is a P2 to P2 cable.
Learn more about this solution : http://www.directproaudio.com/product.cfm?directid=53184
Be sure to verify if 1AVCenter hasn't only picked up the wrong line, and all you would have to do is select the right one.