thanks for the links guys
Koiman, that looks like a beaut, like you say, can't go wrong if it's free. I may try burning one tomorrow and see how it works. I've got the link for
setting up a Behringer Feedback Destroyer. There's a speadsheet download that has the RS SPL Meter correction values already factored in. Should make it a breeze.
Bray, that's the one I was thinking of, not "Rane" - "Rives". The disc itself is very similar to what I was thinking of. Are the test tones at 1/3 octaves sufficient to tame frequency response???? Or should someone be more accurate with smaller increments????
thanks so far, keep the suggestions/comments coming!