Sennheiser Orpheus HEV90
http://www.gizmodo.jp/2013/01/_ces2013_orpheus_he90100.html

Woo Audio WA-234 MONO
http://www.234mono.com/

HiFiMAN EF1000
http://hifilounge.co.uk/hifiman-ef-1000-headphone-amplifier

FOSTEX HP-V8
http://www.phileweb.com/news/audio/201508/03/16190.html