I was about to buy a used First Watt for my headphones. That was in the $2 - $3k range. I came across some positive reviews on the Schitt Aegir that said they were about 80% of the sonic goodness of the FIrst Watt amps. I tried it out for $800 new and have been very happy with that amp. I use it with the Class A Schitt Mjolnir 3 preamp for headphones. Both are a bit hot running but a very nice Class A sound.
In a few years there will be some used CODA S5.5 amps (50 watts Class A) coming up for sale. I will likely replace the Aegir 1 with a CODA S5.5. I like CODA over PASS. I have a CODA #16 and that is my best amp.