Well as far as tube amps, I have a ZanaDeux that I bought with my Grado GS1000 and was happy until I heard the HE 1000. I was told that the Zana Deux is impotent for driving the HEK. I also have the WOO Wa7 and that can't drive it either (I was told). Now I have to buy another amp for a 3k headphone purchase? After all the praise of the MacIntosh MHA 100, I am smitten and will need to save up for it but can't wait on the HE 1000 purchase after falling for them at the Long Island meet. There is no showroom in New York City where I can compare various amp pairings with the HE 1000, very frustrating. What about the AUDEZE Deckard vs OPPO HA1 vs MicroZOTL 2.0 or anything else that will come close to the king above for under 2K?? Will the MicroZOTL 2.0 be powerful enough? I briefly heard this combo at the meet and needed to turn up the volume knob to nearly 90% on some recordings. Had the same problem with my portable rig using the Cypher labs Theorem 720. Love that little Amer/DAC for travel but just isn't nearly powerful enough to drive the HE 1000 to their potential and don't think there is another reasonably priced portable (not transportable) DAC/amp for the iPod that will work.
I believe that was my ZOTL at the LI meet...I'm not sure what happened, some problem with my tubes (I rolled some new ones) or the source (the Mojo LPS I was using stopped working when I got home, maybe it was already giving some sort of problem at the time). I'm listening to it now, if the volume is any higher than 10 O Clock, it would be painful. 9-10 is generally where the volume stays (and I'm 63 years old...my hearing is likely worse than you younger ones out there).
You're never going to be able to compare everything in 1 place, doesn't exist. Some companies allow you a home audition for a number of weeks (I know LTA who sell the ZOTL do this, others as well).
Stereo Exchange in Manhattan has the McIntosh, I heard it there, it is really nice sounding (but expensive), and they weren't set up to compare to other amps that day (and wouldn't be able to compare it to the ZOTL anyway, they don't carry it). I'm not affiliated with Linear Tube Audio in any way; I did review the ZOTL, and I have that connection that owners of gear they live have, they tend to think their stuff is the best, whether they are Honda owners or DAC owners, but I love the ZOTL. You can certainly check the ZOTL thread, there are many happy HEK owners that post there. But, hey, I'm sure you can find something that floats your boat, I don't really think the HEK is THAT difficult to drive, not like, say, the HE-6 (but it is revealing of what is upstream). This happens with all audio gear...if I want to compare, say, a Krell and Naim amp, I may have a very hard time finding a dealer that has both. My only other thought is, if you're in the NY/NJ area, and you know folks with some of the gear you want to compare, you could set up a mini meet/shootout. I don't mind my house in Central NJ on a Sunday I'm free, could be fun. (listening to The Band epononymous album, about 9 O Clock, ZOTL/HEK, sounding GREAT!)
OK, gotta go walk the dog in this 90 degree heat....