I really, REALLY don't think that you're going to find the HD 800 suitable for ANY kind of portable use. They will be big, they will be fragile it's probable that they'll play just as loudly inside out. It's a hard thing to get your head around if you've never used an open can before.
The HD 800 is a premium hifi can and it's meant to be used on a hifi. Coming from Skullcandy of course the E7/HD 800 combo will sound totally amazing, but if you ever hear them well amped you'll never want them out of a portable again.
I'm with ClieOS - save your money for now and buy some nice IEMs or portables to pair with your E7 and drop the other $1000 odd on putting together a home rig. I promise you'll end up much happier.