I know they're not very popular around here, but I've always enjoyed the Beyer DT880 every time I've heard them. And I see them for US$242.something on shopping.yahoo.com.
I think the big question is whether or not anyone has run Sextetts off a Pico, and whether the amp is up to the task. I thought the Sextetts were power-hungry headphones, and although the Pico is very good, is it up to the task of Sextetts? Anyone ever run Sextetts off a Pico?
An RKV Impedanzer or equivalent. What this does is "show" the amp a higher impedance. Someone can probably draw you up a circuit for it, but I think we established it's just a couple of toroids.
Or just listen to your Beyers. (Or find a higher impedance pair of headphones whose sound you enjoy.)
Or get another amp.
See, that's a perfect example. If one examines a meme too closely (I.E. if one only observes one example without understanding that it is, indeed, a meme), it resembles entropy. But there's just too many/much of them for it to be entropy.