Guys, these things don't need much in a way of an amp. I've been playing the review unit all day on my FiiO X5 which has a weak on board amp made for IEMs and portables, and the THX00 doesn't sound underamped one bit. The X5's colored amp plays very nicely with the THX00's tuning as well. Last night I got in some time with both Project Sunrise 3 and Horizon 3, surprisingly I'm liking these more at the lower current Horizon 3 that puts out 300mW to 25ohms where as the Sunrise 3 is double that (both can be switched between 3, 35, and 125ohm output).
Lots of fun but without getting too colored. I'm really liking the tuning on these so far; jazz, acoustic, vocals, and anything that plays into a bass boosted sound. The phones behave and have a nice tone when listening to most of my music but get in some Unfinished Symphony by Massive Attack with it's deep sub-bass action or some rap/electronic/etc that has a big bass sound and these things turn into party phones. Those who own mostly neutral phones like myself will really enjoy the contrast and those who favor warmth/color will find some masterful fun tuning in these. Hats off to Fostex and Massdrop for getting this phone out in the world at such pricing! More reason to be excited for those shipments!
Actual review will be up in a few days.