I too am wondering how grados sound with the E7. I'm intending on picking one up mainly for the DAC and the possibility of getting an E9 later. If I'm able to snag one shortly, I'll be sure to write about it.
Its sounds pretty darn good. I haven't had a chance to really listen to it with a better DAC for any sort of extended period of time, but you won't be disappointed with the E7. Right now I regularly listen to my grados out of my E9. I have a little dot 2+ but grados sound better out of the E9. The LD2+ is more for the fostex and d2000.