Like I said before, it had no problem driving the O2 Mk1 at all. Everything else was also a piece of cake (Jade, HE60, SR-404LE, SR-Lambda Signature, SR-Lambda, SR-Gamma Pro with wood cups/O2 Mk1 pads. It could cleanly drive the O2 loud enough with infected mushroom to vibrate the skin around my ears and tickle my ear drums. It was quite sensitive to the sound of the DAC and transport being used - ruthless in fact.
950's are as easy to drive as a Lambda Sig, and since it can sound good with my HE60 then the ESP-950 would be a no brainer.
Don't forget I'm already first in line.