This is the HD 6x0 chassis with the HD 700 driver dropped in. No confirmation yet on what if any tuning has been done to the driver to get it to play nice with the change in enclosure. Either way, I am skeptical that this will be an upgrade to the HD 650 or even HD 600 across the board given the issues with the HD 700 in both measured and sonic performance.
According to the project page, it comes with the same cable as the HD 650, that is 1/4" with a 1/4" to 1/8" dongle adapter.