I may skip the attenuator as well, I don't want anything that can interfere with the signal. I'll call up Oade again tomorrow, see if maybe I can buy a 3rd 4061 and just return the one that matches less. I figure if the DPA spec is +-2dB and I have a 3.5dB difference, I've pretty much got two that are at opposite ends of their tolerance. Worst case, I'd end up with a 1.75dB difference if the 3rd mic was right in the middle. We'll see.
Or maybe just buy that MMA6000 I've been looking at