See post #7 from maty in this thread. That was a pre-PFFB early testing board. That was at 6 ohms, .01 THD + N. I think a later sample hit .007% THD + N without PFFB enabled in to 3.3 ohms.
I noticed that you guys cite THD+N < 0.01%, 0.3W – 200W, 4Ω but your AP THD graph shows hitting .02% THD...