I only have a couple of hours on both the Geek Out V2 and the Mojo driving a pair of HD800. My *very* preliminary conclusion Hugo > Mojo > GOV2... but this could change. First, I used the GOV2 single ended. Logic (and reviews) suggest that it's much better running balanced. I will be able to do this later this week once I make a converter cable. Second, I wasn't listening to them back to back though both were compared to a HiFi-M8. In the next couple of weeks I will do a head to head between the GOV2 balanced and Mojo driving HD800 and Westone 5ES.
--mark
thanks.