Mix Magazine says:
“…if you’re looking for the best there is in an IEM that brings you an unparalleled and trustworthy listening experience, you should consider the UERR at the top of your list.”
Mix also says:
After hearing both the original and UERM, the latter is a sizable leap in quality, and according to UE’s Vincent Liu, it’s all about the tech. Recent developments in specialized tooling allowed UE to be able to control the diameter of the sound channel down to .1 mm. The UERR also employs a balanced armature driver that pushes the upper range of the monitors above 18 kHz.