Introduction

Ultimate Ears is one of the most recognized in-ear monitor brands out there, for a good reason. The company produces a wealth of different universal and custom in-ears, straight from $30 universals to six driver custom in-ears priced at well over $1000. Today we will be taking a look at a somewhat unusual set of custom in-ears.
Ultimate Ears' newest addition to their already booming line of custom in-ears is the oddly named "In-Ear Reference Monitors" (IERM). These in-ears are unique in the sense that it is Ultimate Ears' first high-end in-ears that have come out of collaboration with Capitol Studios. Ultimate Ears have effectively quit the balanced armature race with the IERMs, they feature just three balanced armatures hooked up to a three way cross over. Less is more, one could argue and with balanced armatures there is some truth to this saying.
Controlling phase coherency and volume matching is incredibly hard with in-ears and less probably makes is easier to get right. This approach is different than Jerry Harvey Audio's which have always preached more drivers equals better sound due to a reduction of overhead. In between is Westone with their recent addition to the high-end in-ear market namely the ES5s. We take the Ultimate Ears Custom In-Ear Reference Monitors for a spin and see how they perform compared to the eight driver JH-AUDIO 16|Pros and the Westone ES5s.

Specifications

• Input Sensitivity: 98 dB/mW @ 1 kHz
• Efficiency: 112 dB @ 1 kHz, 1mW
• Frequency Response: 5 Hz to 20,000 Hz
• Impedance: 21 ohms @ 1 kHz
• Internal Speaker Configuration: 3 proprietary precision balanced armatures
• Noise Isolation: -26 dB (100% acrylic housing) and -32 dB (soft silicone material option)
• Input Connector: 1/4” jack adapter gold plated; 3 pole 1/8" (3.5 mm) standard jack
• Warranty: 1-year limited hardware warranty.

The specifications list unveils nothing surprising, except a somewhat less far fetch frequency response band than usual. 21 Ohms and 98 db/mW @ 1 kHz means that these will require little to no external amplification to sound their best. There seems to be a soft silicone option as well, even though it is not available on Ultimate Ears' new Logitech sub-site.