Hi Todd,
I don't have an answer for you, but I think I'm getting a Smack for christmas from my wife, and have looked around and don't see many 4 pin xlrs, but if you found the right one, could you let me know which one it is.
Also, being a total newbie to balanced headphones (except for hearing them here and there over the past couple of years), I actually have no idea if the chassis mount is supposed to be the male or female connector -- and is this the same for 3 and 4 pin connectors?
It looks like Furutec doesn't even make a 4-pin type, though I certainly wouldn't limit myself to what they offer.
I just scored a open box special on HD800s this morning, so I will want to use them in balanced mode on the Smack, but with adaptors on the Crack.
-- Jim
Jim Rebman -- recovering audiophile
Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).
s.e.x. 2.1 under construction. Want list: Stereomour II
All ICs homemade (speaker and power next)