Ditto. I find my ZX1 didn't have enough juice to drive my ADs nicely. I did note that you (@dleblanc343) mention "for fun". As such I was investigating the PHA-2 add-on but eventually felt using the ZX1 as my DAC & analog-LOD out to my TUR-06 for the AD's.
I kinda figured the ZX1 would not power full-size cans but I do like the Dogs... I'm after a set of full-sized headphones just got to get around choosing some, those Fostex TH-900's look pretty sexy as well.