Well, I've used my Denon mic before, that has a pretty good length. Or, if your using a Radio Shack SPL meter, it has an output jack, so you can just plug a long cable with RCA ends from the meter to the sound card jacks, you might need to get an adapter cable that goes from RCA to the jack size for the computer soundcard, I think 3.5mm or something like that.

My HTPC is hooked to my projector, so I can watch the graphs as I took measurments.

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