Another vote for the MicroZOTOL2, but I haven't heard the megabuck/high priced spread. Have compared it to RSA HR-2 (with the HEK), and I'm now the first on a tour of the Airist Audio Heron 5, a solid state, single ended dedicated headphone amp, and is selling for about $2K. Without going into detail here, I'll say that I like my ZOTL best of the amps I've used so far. I wouldn't be surprised if the high end RSA or Cavatelli amps are better, at multiples of the price, but this is a killer amp for not a little money, but not up with the most dear gear. (I'm burning in the Liquid Carbon, initial listening didn't change my opinion, LC is nice, costs less than the ZOTL, more "transportable", but I liked ZOTL sound better...but, break in is supposed to make a big difference in the LC, so I'm burnin' for a few more days before comparing again).
My $0.02.