Recently popped my Caldera lava spout...
Currently running it off a Burson Soloist 3XP with Sparko op-amps. Of course it sounds fantastic. Most impressive ZMF thus far. That all being said, I had my heart set on picking up a Cayin HA-3A as an entrance into the world of tubes, but doing my research like a good lil'audio boy, it sounds like the HA-3A isn't a great pairing with the Caldera unless you manage to find holy grail tubes?? Consensus seems to be keeping it on SS is best and of course the Bliss is better, but the Bliss is $1~2K more so one would hope it would be...
I suppose I'm wondering if anyone has any thoughts on moving from a Soloist to the Cayin HA-3A, if there are other amps I should be considering instead, and/also if tube amps or similarly priced SS amps would even be a better pairings than what I already have (a relatively well respected SS amp, the Soloist)?
I love the Caldera off my Auris Nirvana (tube selection is important, but based off 12au7 and EL34, even NOS tubes are easy to source and not too expensive) which you can find in head-fi classified at prices sometimes near a Bliss. For solid state options, you can get great CFA-3 builds on head-fi classified for around $2+k (which personally I prefer to the Bliss, though it's neither better nor worse, just different: more open high frequencies/bigger stage vs. the more dense Bliss tone)
Beyond that, come and join us down the amp rabbit hole (aka as "The (Un)Official Amp Thread For ZMF Headphones" thread):
https://www.head-fi.org/threads/the-un-official-amp-thread-for-zmf-headphones.965309/