Rev 1.6 and 1.7 differences?

I am just finishing up calibrating a v1.7 a12, and everything's looking good. I already have an existing v1.6 a12, and I intend to use them in stereo every now and then. Is there anything different between the two revisions that would affect the sound in any discernible way? I did a quick search, but found nothing on this. Thanks, love the preamps.