I am not going to be able to conduct the unmodded HD800 vs the K712 Pro review, but thanks to those that have given their impressions here in this thread.
Every time I listen to the K712 Pro I am impressed with the detail and soundstage. They are definitely keepers until I can move up to the HD800.
Like I've alluded to earlier, I owned the HD800 before this and this is still satisfying enough to hold me over for a few months until I can upgrade again. Though, I'll likely go the K812 route next depending on impressions.