David, yes I will be evaluating headphone performance as well especially since the mystery amp, a Decware Taboo MK IV, is actually a headphone amp that is also designed to drive speakers. My current long time headphone amp is a Melos SHA 1 which, despite its age (mid ’90’s), fixed power cord and single tube circuit, has held pride of place against all challengers, most recently the VR L2iSE (which admittedly is not designed as a headphone amp). My headphones are Hifiman HE1000se.
Despite my curiosity to hear the V2 driver, I’m approaching the decision not to upgrade simply on the basis of the new driver’s 3db loss of sensitivity. Even if one of the solid state amps wins the up coming shoot out, I think I would still want the original driver’s 93db sensitivity to check out other lower watt tube amps in the future. One of the great attributes of the original Nen driver IMHO is that it behaves as if it has much higher sensitivity, say 96 or 98db, probably because its load doesn’t dip below 4 ohms. I know Vinpic is happy with the upgrade and its pairing with the Enleum 23R, so if that amp emerges head and shoulders above the rest, I might reconsider. We’ll see.