Media Players and Browsers will use a reproduction line to play their audio and almost all audio drivers for Windows map the reproduction lines to a mixed audio recording line that will have a name like 'Stereo Mix', 'What U'Hear', 'Record Master' or other.

Recently however some manufacturers have disabled this mixed audio line, that's the case of Dell's SigmaTel new audio drivers in which you won't find the mixed recording audio line.

1AVCenter will automatically select audio sources for you but if your audio driver doesn't support certain audio lines like Dell's SigmaTel new audio drivers then the audio line used to reproduce the audio you actually hear isn't there to be recorded.

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If this is your case it can be solved by cabling from Line-Out to Line-In with a P2 to P2 cable.

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Even if the line is installed 1AVCenter might pick up an audio line that isn't in fact the correct one and in this case you'll have to change the audio line yourself using the 'Profile Settings'.

There you'll see all audio lines that exist in the system for you to select and verify which one works.

In case of trouble recording audio because you can't hear it at all after recorded it's fairly safe to say that the current capture profile is most probably using an audio line that's not receiving the audio input. So verify what is your case and follow the instructions to solve it.