Performance

The IERMs were put through their paces after 100 hours of burn-in time. In order to test the in-ears a few different rigs were used:

• iPhone 4 - Headphone out
• iPhone 4 - Digital out - Fostex HP-P1 headphone out
• iPhone 4 - Digital out - Fostex HP-P1 line out - RSA The Protector, both single ended and balanced out
• Head-Direct HiFiMAN HM-801 - Headphone out (balanced module)
• Head-Direct HiFiMAN HM-801 - RSA The Protector, both single ended and balanced out

The new Ultimate Ears In-Ear Reference Monitors are pitched against the usual suspects: JH-AUDIO 16|Pros (eight driver, three way cross over) and the Westone ES5 (five driver, three way cross over). Ultimate Ears decided to go with a shallow insertion just like JH-AUDIO did with the 16|Pros we had for review.

Right from the beginning of the test the IERMs performed admirably, the fit was perfect and the new type of cable seems both durable and less microphonic than that of the ES5s and the JH-AUDIO 16|Pros.

Bass quantity wise these are no match for the JH-AUDIO 16|Pros or the Westone ES5s for that matter. The IERMs are simply not geared for the low end rumble the two other deliver. The IERMs simply do not thrive once the frequency gets below 50 Hz, here the definition and presence drops dramatically, which is a real shame.

Amount wise the IERMs are not exactly bass light, but its extension and sub-bass control could have been a little better, especially with the price tag in mind. The dialed down bass could be due to the fact that these in-ears are trimmed for front of house mixing, but then again the de-emphasized bass will lead to some quite overshot bass equalization if they are used as reference. The mid bass is very well defined on the IERMs, the other two have a slight hump in the frequency response here which also gives them their warmth. The greater linearity makes the bass and midrange seem much more integrated.

Coming up from the bass to the midrange and the IERMs begin to prove their worth. Compared to the other two the midrange of the IERMs is less colored, has a more natural decay and a bigger sound stage to boot. Due to the less powerful bass and a delicately balanced treble response the IERMs come off as rather mid-centric. One of the things that the IERMs do extremely well is acoustic instruments, the timbre is simply spot on.

The midrange lacks the warmth that both the JH-AUDIO 16|Pros and the ES5s deliver. The leaner sounding mids of the IERMs makes it much easier to pick out tiny details. On a well mastered record they simply make the other two pale in comparison. It is not a night and day difference in terms of details, but the lack of coloration gives the IERMs a very unique sound. The somewhat dry and neutral midrange is not that pleasant to listen to on ill mastered music, but on the few rare occasions where the mastering is supreme the super resolving midrange makes its point. It simply takes vocals and acoustic instruments to the next level for an in-ear monitor. That combined with perfect timbre, and near perfect separation between instruments in all three dimensions, makes them very engaging to listen to.

Upper midrange and treble performance of the IERMs is likewise better than its main competitors. The treble is über resolving, and linear until inaudible. Like the transition from bass to midrange the transition into the treble area is painless, there are no sibilance issues.