Overall resolution levels are extremely good, though both the Westone ES5 and JH Audio JH16 Pros offer very stiff competition and may offer even greater resolving power, though only by a hair. But the tradeoff is that no other in-ear monitor I’ve heard can top or even equal the effortless smoothness and overall balance of the IERM’s response curve.
Ultimate Ears did an absolutely masterful job of molding the custom-fit earpieces of my sample pair of IERM’s, so that they achieved an excellent seal in my ear canals, while also serving up a heaping helping of comfort. What makes the IERM so fun to use is the fact that the earpieces are easy to handle and seem simply to “snap” into place with a minimum of fuss and bother (whereas some earpieces can take a fair amount of work to insert properly). Over time, I’ve come to think that translating ear-mold impressions into great fitting custom earpieces involves both science and art, and it’s obvious that UE has mastered both sides of that equation.
One disk that highlights a number of the IERM’s strength is the eponymous jazz recording from Floratone (Floratone, Blue Note/EMI)—a band in which eclectic guitarist Bill Frisell and his cohorts figure prominently. As is often the case with Frisell’s projects, the beauty of Floratone not only hinges on angular, otherworldly melodies but also a variety of sometimes dark and brooding and sometimes light and ethereal textures and embellishments. The result, on most tracks, is a densely layered sound that, through some headphones and many loudspeaker systems, runs a serious risk of turning into a complicated and incoherent sonic “mush.” But through the Ultimate Ears IERM’s no such problems occur. Instead, there is real weight, power, and definition on bass passages, while complicated instrumental lines and texture are cleanly presented and beautifully delineated.
Put on the track “Swamped” from Floratone and you’ll immediately hear the round, sweet, and somewhat chime-like signature sound of Frisell’s guitar take up the melody, supplemented by the deep, earthy growl of a syncopated acoustic bass line and a clear, simple rhythmic pattern played predominantly on the percussionist’s high-hats and snare drum. What’s so pleasing about the IERM’s presentation on this track is that each instrument is given its due, so that each sounds full, complete, and three-dimensional—independent of what the other instruments are doing. Nothing is compressed or exaggerated, so the music simply unfolds naturally without any need for embellishment.
Later, on “Lousiana Lowboat”, a different set of challenges arises, as we again hear Frisell’s guitar accompanied by drum kit and bass, but this time with the output of the guitar and bass channeled, in part, through electronics effects boxes. Thus, we hear the natural sound of the guitar and bass overlaid with effects that extend but also fundamentally alter the instruments’ natural voices. The inherent accuracy and clarity of the IERM’s make it easy to tell exactly where natural instrumental timbres leave off and the effects-driven voicings begin. But there is also on further sonic challenge, as the bass drum and tom-toms on this track are very low pitched and tricky to reproduce well (indeed, the voice of the lowest drum is positively subterranean). Here, the IERM really shines as it wades right in and delivers shuddering, ultra low-frequency bass drum thwacks without skipping a beat, and while effortlessly capturing the skin sounds of both the bass and tom-tom drum heads.
Finally, to really appreciate the benefits of the IERM, it’s worth putting on some material whose content is strongly midrange-centric, if only to hear how smooth and suave-sounding the IERM’s mid-band response really is. A good example would be “I Am a Town” from Mary-Chapin Carpenter’s Come On, Come On (Columbia). Two things are gripping about this track: first, the timbre’s of Carpenter’s voice, which are at one breathy sounding yet at the same time earthy and full-bodied, and second, the absolutely gorgeous voice of the acoustic bass (playing way up high in the cello or even viola range) that accompanies Carpenter’s voice throughout the song. The IERM’s do a great job with Carpenter’s voice, capturing both its high, lilting, almost whispered breathy qualities, but also revealing its earthier, lower registers, which carry inflections reminiscent of Southern gospel. But add to this the bass (whose upper register sounds amazingly smooth and evocative) and you’ve got something truly stunning. There is really no other way to put this but to say that the Reference Monitors make the bass sound about as vibrant and realistic-sounding as any headphone possibly can. Through the IERM’s, there is a powerful, you-are-there immediacy to the bass' sound that is truly breathtaking (which is precisely why high-level accuracy is something worth pursuing).