I was reading the tour comments and I noted a well written comment from one reviewer saying he didn't find the listen enjoyable. I thought something must be up, so I blew the whistle to call the Dog home.
I left a screw out on the baffle assembly. I built all the first units, so I own it. The screw wasn't loose under the pad so this was my error in assembly. The effect of that screw missing is to non-linearize and reduce the bass and harden the sound. The hole was likely covered well by the pad but as the pad compressed from multiple shipping and uses (as should be expected) it probably allowed the hole to be exposed.
I've fixed it up and will send it to the next reviewer, MLE. If any of the earlier reviewers want to hear it again it's worth it.