http://imgur.com/a/4cGbS Gallery of 3 recent measurements. Done on tweeter axis, outdoor at 1m, tweeter is 82 inches in the air. MiniDSP usb Mic, Behringer U-Control UCA202 as USB DAC I don't normally do waterfall plots when I do a review, but I wanted to start incorporating them in the future. Except every measurement I've taken shows almost perfectly matching slow decay from about 6khz to 20khz. Because the problem is so uniform, I'm assuming it some hardware issue. Has anyone seen anything like this before?