Effective number of bits---or why "you have to keep software at full volume" is nonsense

[jcx]

dynamic headphones do range over 40 dB in Vdrive sensitivity when low Z iem are compared with "studio monitor" 300, 600 Ohm headphones, particularly if Orthodynamics are included
 
some iem only require 200 mVrms to reach 120 dB SPL, some other full size headphones over 20 Vrms - you are going to have an amp input noise problem if you use a Av 20 amp suitable for K240 or HE5 with UE, JHAudio iem