Currently I have the Anandas, HE4xx, AKG Q701, B&O H6 and a modded Blon B30. Besides that, I have several IEMs (Moondrop B2s, Tin P1, BQEYZ Spring one, etc...). So, low impedance output is a must for me. They are all powered so far by a E30+L30 stack or a NX4 or ES100 or a LG G7 smartphone.