Drop the receiver, unless you're planning to power a pair of near-field bookshelves. I'm not familiar with that particular model, but based on specs, I wouldn't put my HD700s anywhere near it.
Spend the money, buy a nice dac/amp. Or something relatively cheap, that actually pairs well with the HD700s. Like the HRT Microstreamer.
Don't spend 500+ on a headphone, then run them straight out of your mobo. Not worth.