I forget where I initially read www.raymondaudio.nl but
I did recall that Raymond has a speaker measurment jig that
works with a soundcard rather than a stand-alone system.

So I brought it in here for comment.

Raymond also has a good writing style and some other
worthwhile projects at his site.

Be sure you send him some props if you find it useful. :-)

• Raymondaudio... Speaker measurement jig middle of page

The amp is inexpensive and easy to build, and it performs well with a couple of AA batteries for power. The microphone will get power from this circuit, so be sure and observe proper polarity. The Panasonic microphone is pretty sensitive so it will pickup everything in the room. Be careful not to overdrive your inputs; Just turn down the gain.

This looks to be something of a project for the FAQ.