[Three]

Decware CSP3 is nice, and also functions as a preamp:

https://www.decware.com/newsite/CSP3.html

Mapletree Audio also makes some nice ones, but they’re pretty low key and you won’t find much info on them:
https://www.mapletreeaudio.com/#headphoneamps

 

[jonharrison11]

Man that’s gorgeous, wish my wallet was on par with my eye

 

[jimbop54]

http://www.electronluv.com/