Have the KingSounds here on loan right now. Pin out appears to be the same as Stax pro bias. Running from the normal bias jack of my SRM-T1.
Spent some time at the dealer's place with the KS amps for about an hour. The SS amp sounded better to me. More control, blacker background, etc. The tube amp sounded wimpier. SS amp got really hot near the top...I think they're gonna have to look at more adequate heatsinking. Both amps were RCA input only (SS had a loop out as well). He popped the top off the tube amp to change the tubes, so I got a peak at that at least. 2x 12AX7, 4x EL84, and 1x dunno. I'm pretty sure it was some kind of rectifier tube. 6-something-something-L I believe.
Looks-wise, the headphones scream MADE IN CHINA. The plastic is really cheap toy stuff and I wouldn't try to bend them much. The positive to that is they're super light and quite comfortable on my head. I don't know if somebody with a bigger head can wear these without snapping the headband though. Pad material feels decent (better than ESP950), and they're rather large in diameter so my ears don't really touch anything. Again, comfy. Cups don't have much travel to move up and down, but can swivel from side to side freely so you can fold them flat if needed (think Grado pizza box). Cups don't really seem to be able to tilt much...it looks like they should but I don't want to break them. Cable and connector both pretty nice.
You can't really see the stator design unless you hold it up to a pretty bright light. Looks to be standard perforated metal, hole diameter about 60% size of those on the grill. They're also using pinwheel/spoke bracing as found on the SR-Omega/SR-009. Think 009 brace but with a quarter-size hole in the middle and 12 spokes.
I'll post impressions of the sound when I have some more time with them.