The "problem" is, so far out of the several (3, I think) Yamaha he tested recently, only one, the RX-A1080, did not make it to his recommended list so he doesn't have much to complain. I re-read that one and found no evidence it suffered from the same thing that the Denon did, in other words, no downmix bug in the RX-A1080.
Also the pre-out issue with the Yamaha isn't unexpected as Gene sort of found the same kind of limitation when he measured the slightly lower rank RX-A860.
Amir could barely measure the Yamaha
RX-A1080 with pre-out at 2 V:
"The unit though was at the verge of shutting down despite me leaving speaker terminals disconnected. If I just dialed up the volume 0.5 to 1 dB, it would shut down. So for the rest of the measurements I went with 0 dB volume level."
I thought Gene did work with Yamaha on the CX-A5200, hopefully he would press them on making their AVR pre-outs more robust too.