Ultimate Ears' new Reference Monitor in-ear headphone is a very different take on the state of the art. UE collaborated with EMI Music's Capitol Studios to design this headphone for recording, mixing, and mastering engineers. The UE engineers submitted a number of prototypes to Capitol and other beta testers for feedback before arriving at the finished Reference Monitor. I'm no engineer, but I think the Reference Monitor is the best, most accurate-sounding in-ear headphone I've heard to date.
Right, I know some of you must be thinking, aren't all headphones designed to be accurate? Once you listened to a number of headphones you'd know that's far from true; they all sound very different. They can't all be right.
I spent a lot of time comparing the Reference Monitor ($999) with Ultimate Ears previous and still available flagship headphone, the($1,350). The UE 18 Pro is still very impressive, but it has a prominent bass bulge the Reference Monitor lacks. The new design is more accurate, with a flatter frequency response, so the Reference Monitors have a more audiophile oriented sound perspective.
That said, I prefer the UE-18 Pro's extra bass when I listen in noisy environments, like the NYC subway. There, the Reference Monitors sounded a little bass-shy because there was a lot of low-frequency background noise masking the music's bass. The UE-18 Pro's bass bulge compensates for that to some degree, so if you use headphones in noisy environments or prefer a fuller tonal balance, get the UE 18 Pro. In quieter places the Reference Monitor's bass will be more accurate, and its bass goes even deeper than the UE-18 Pro's.
Philippe Depallens, Ultimate Ears' VP & General Manager filled me in on the details about how the Reference Monitors differ from the company's other custom in-ear models. The Reference Monitor sports three individually tuned, balanced armature drivers (bass, midrange, treble) in each earpiece; the UE-18 Pro has six individually tuned, balanced armature drivers (double bass, midrange, treble) in each earpiece.
Depallens also told me the Reference Monitors are available in two slightly different versions for the same price, one with a standard acrylic "shell" (or body) that provides up to 26 dB of sound isolation, or the Reference Monitor can be ordered with a soft silicone material over the acrylic shell that provides up to 32 dB of noise isolation. I had the standard version, which blocks outside noise at least as well as most battery-powered noise-canceling headphones. External low-frequency noise/rumble from buses, trains and jet engines are as much felt as heard, so the noise isolation (or noise canceling) can't block that kind of noise.
Tal Herzberg, the Grammy-winning recording engineer and producer who has worked with the Black Eyed Peas, Pussycat Dolls, and Mary J. Blige, uses Reference Monitors. He described the Reference Monitor this way: "What is unique is that I find myself not worrying about environmental noise. Once I put these on, the isolation is so good, room noise is virtually eliminated. All I hear is the natural, dimensional sound the monitors create, allowing me to accurately record and mix."
I started my auditions with the "French Dub Collection" CD, which amply demonstrated the Reference Monitors' bass dexterity and ultradeep bass extension. The UE 18 Pro sounds like it has much more bass than the Reference Monitor on most recordings. The difference is the UE 18 Pro has more midbass, (I'm guessing around 70 to 100 Hz bass), but the Reference Monitor has flatter overall bass, and superior low, 30 to 50 Hz bass oomph. To my ears, the Reference Monitor's bass definition is well ahead of that of the UE 18 Pro, and all other custom in-ear models I've heard. That said, the bass still doesn't have the weight and impact of full-size, over-the-ear headphones.