Was it this thing?
I'm amazed by the 1.6 ohm output impedance on a $6 800 amp. I'm further amazed by the fact that they dare call it "plays nicely with all speakers" (emphases theirs). If made to drive very low-impedance speakers, a large amount of power would be lost in the amp itself.
Yes, that's the one. Even with my not-so-low impedance speakers, there was a lot of frequency response variation because of that. I'd be interested in seeing if the source of some of the odd measurements is the impedance transformation, the power supply, or something in the input/driver stage design. If the impedance transformation circuit is clean, I can imagine that this technology could be used to build an amp with very good performance- output transformers are indeed the chokepoint in tube power amp design.