Interesting product. The low noise and attention to phase timing is interesting at $750. Take SABF reviews with a boulder-sized grain of salt; that forum is dominated by a few egomaniacs with a fetish for mid-fi gear and an unfortunate culture of group think -- as if a high-end amp could be appreciated with their HD650s.
GUTBI listened to this amp with HD600s, the HD800s, HE6s, and the AKG K1000. This amp can definitely be appreciated with HD600s. I only own the HD600 and had a friend over who has the other three headphones and I still bought this amp.