At the time, I found the HD650's more comfortable than the ESW10's. I now have an M^3 instead of the Headroom amp, and the gain 11 (I think) on an amp with a stepped attenuator makes it hard to really get the volume I want out of the ESW10's. Unamped, the 10's clearly beat the 650's but on the M^3, I find I can listen longer using 650's which means to me, more enjoyment.
Hope that helps?