Is there any difference in audio quality between my sound card's "Line In" and "Microphone" jacks? Both are the same kind of 1/8th. I was fooling with my system and it seems there's less feedback and crackling on the mic slot than the line in slot, so I'd prefer to use it.

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NEW MIX [Feb/March 2008]

Line-in is designed for about a 1 volt amplitude signal such as from most consumer equipment like CD players etc, while mic-in is designed for a non-amplified microphone signal which is about 40 db lower, or aprox 10 millivolts amplitude.

My guess is they should be about the same quality, but you should use whichever best suits the voltage output level of your signal source.