I’ve gotten excellent results all the way from the Massdrop CTH, Woo WA6 (in low-impedance setting), the iFi Pro iCAN (especially in tube mode), with Schiit’s Ragnarok, Woo WA5-LE Mk2 and WA234 MONO Mk2.
They sound great out of units like the Chord Hugo 2 and Sony NW-WM1Z as well.