Regarding the Van Alstine 400R--tried that with the 1.7's years ago and sent it back. On paper it looked to be a great match but in listening, I way preferred a Marantz integrated! Was never able to relax and let the music wash over me in a way the less expensive Marantz did.Interesting. I almost bought the 400R for my .7s but instead opted for Exposure 3010S2 monoblocks. I too was able to get very decent sound from a mid-tier integrated but the Exposures are a nice upgrade with plenty of drive.
I am surprised by your results though, as Van Alstine is a big proponent of robust power supplies.