Etymotic Research didn't jump on the headphone bandwagon. Rather, the company helped hitch up the horses and get the wagon rolling. With roots in acoustic research and hearing aid design, Etymotic developed its first high-performance, noise-isolating earphone, the ER4, back in 1991. The company currently offers a variety of earphones at lower price points, but various iterations of the ER4 have remained the flagship offering. In its latest update, Etymotic has introduced two versions: the ER4SR (standard response) and ER4XR (extended response), both of which cost $349.

Etymotic (pronounced "et-im-oh-tik") means "true to the ear," and that pretty much sums up what the company is going for with the ER4's sound presentation: accuracy. In describing the difference between the two versions, Etymotic describes the SR model as a "must have for discerning engineers, audiophiles, and consumers wanting the most accurate in-ear earphone available." Meanwhile, the XR is designed for "music lovers and hi-fi enthusiasts who want uncompromising accuracy in the midrange and high frequencies, but appreciate a bit of extra presence in the lower end." I confess, I fall more into the latter camp than the former. I'm not looking for Beats-style bass or anything like that, but I do appreciate a little bit more low-end presence than many audiophile-oriented headphones deliver. So, when requesting a review sample, I opted for the ER4XR.

Each ER4XR earphone features a precision-matched, custom-tuned balanced armature micro-driver in an anodized aluminum shell; the detachable, replaceable cable measures five feet in length, with an L-shaped gold-plated connector. Impedance is 45 ohms, and sensitivity (which has been increased from previous models) is 98 dB. The package includes a variety of foam and silicone ear tips, a quarter-inch headphone adapter, replacement filters (with a removal tool), a shirt clip, and a hard-shell case to carry it all.

With any in-ear monitor, a proper fit is the key to getting the best performance. Since noise reduction is a big selling point of the ER4, proper fit is even more crucial. As packaged, these IEMs are a universal-fit design, meaning that a custom in-ear mold isn't part of the price, as it is with much pricier IEMs from companies like Ultimate Ears and Westone. Etymotic supplies two sets of foam tips, two large three-flange silicone tips, and two small three-flange silicone tips. However, custom-fit molds are an upgrade option.

To be honest, my first impression of the ER4XR wasn't very positive, and the fault was entirely my own. As I was headed outside to take my daily walk, I discovered that my pair of everyday IEMs, the RBH EP3, had finally given up the ghost, due to a damaged cable. I quickly unboxed the ER4XR, casually popped them in my ears with the preinstalled large three-flange ear tips, and hurried off for my walk. I quickly noticed than many of my favorite walking tunes had absolutely no bass and little to no midrange. The sound was small, tinny, and sterile. Plus, I'm not a big fan of flange-style ear tips, and I found the larger tips to be uncomfortable (they're pointy and extend very deep into the ear canal) and difficult to keep in place.

Folks, that just isn't how these IEMs are meant to be used. Later, when I was ready to give the ER4XR a serious audition, I swapped out the silicone tips for the supplied foam tips, took a few minutes to watch Etymotic's Earphone Insertion Video, and then followed those guidelines to get a more precise fit.

I began moving through some of my favorite AIFF demo tracks on my MacBook Pro, and it was like I was listening to a completely different set of earphones than the ones I originally heard. Both the bass and midrange sounded fuller, and the overall presentation was much more balanced. I could still tell that these are very precise, revealing IEMs, but taking the time to get a proper fit added just the right amount of warmth to suit my tastes. Plus, I found the foam ear tips to be much more comfortable, allowing me to wear the ER4XR for long listening sessions without issue.

I compared the ER4XR with my reference headphone, the B&W P7. While the P7 is an over-the-ear design, it sells for the exact same $349 asking price as the ER4XR and is also aimed more at the audiophile crowd than the mainstream market. I'll highlight just a few of the many tracks I auditioned.

With Tom Waits's "Long Way Home," bass response between the Etymotic and B&W was quite similar--both offer solid but not excessive bass that's clean and controlled, not boomy. The Etymotic IEMs sounded a little more spacious and airy on top than the B&W headphones, and Waits's voice had more texture. With the ER4XR, I was more aware of subtle background details, like the sound of Waits's fingers hitting the guitar's fretboard at the beginning; it just sounded more realistic and nuanced.

In honor of the late Chris Cornell, I cued up "Seasons" from the Singles soundtrack. Again, the ER4XR had a little more sense of air and openness in all of the high-frequency details. I found the top end to be very precise, but not harsh or sterile. These IEMs did a great job bringing out all the character in Cornell's voice as he moves through his range and provides his own background vocals.

With Charles Lloyd's "How Can I Tell You" from the 2015 HDTracks Sampler, the ER4XR served up silky smooth horns, a spacious sound, and clean, crisp bass. With this track, the B&W over-the-air headphones brought out just a little bit more of the deeper stand-up bass, which fell back a bit in the mix through the ER4XR. It worked for me, but others might crave a little more bass.

I also listened to a lot of lower-resolution MP3s, in the 160k to 192k range, and I didn't find the ER4XR to be so revealing that you have to feed them only the highest resolution stuff. These earphones worked great for casual listening, too. The sensitivity is a little lower than that of some competitors, but the ER4XR played plenty loud for my tastes when connected to my iPhone or MacBook. I want to mention one MP3 track in particular: U2's "The First Time" from the album Zooropa. There's a Bono echo track running very subtly in the background of this track that I've really never paid much attention to. I hardly even notice it through most headphones. With the Etymotic IEM, though, I was suddenly quite aware of it--and not in a bad way. It was more like, "Wow, how have I been missing that all this time?"

High Points
• The ER4XR is an accurate in-ear monitor that serves up clean, spacious, nuanced highs, as well as rich mids and solid bass--as long as you take the time to get a proper fit.
• These IEMs provide great noise reduction. Etymotic claims 35 to 42 dB, and I was successfully able to tune out most distracting background noises while auditioning them in crowded public places.
• The supplied cable is detachable, so you can replace it if it gets damaged. Etymotic also includes replaceable filters, in case the installed ones get dirty or damaged.
Etymotic supplies a variety of silicone and foam tips, and custom molds are an option.

Low Points
• The supplied cable lacks a microphone and phone/volume controls. Also, the L-shaped connector may not fit into a bulkier protective case for your phone or tablet (I had to take off my iPhone case that includes a backup battery). And there's no small, soft pouch to stow and go. All of these speak to the fact that, while this is a portable and discreet IEM, it isn't really targeted at the mobile or active-lifestyle market.
• The ER4XR fits deeper in the ear canal than some IEMs, especially when using the flange ear tips--which some people may find uncomfortable.
• The foam tips seem a little cheap for a $350 pair of IEMs. I'm a fan of Comply tips myself.
• The black "L" and "R" markers are small and etched into black casings, which makes them hard to see.

Comparison & Competition
Two recent IEMs that we've reviewed that fall in a similar price category as the Etymotic ER4XR are the Periodic Audio Be ($299) and the Jays q-JAYS ($279). Also in this price class are the Grado GR10e ($400), the Westone W30 ($400), and the Audeze iSINE 10 ($400).

Conclusion
Etymotic's ER4XR is a high-performance in-ear monitor that's accurate enough to bring out the best in your higher-quality recordings but forgiving enough that you can still enjoy any lesser-quality files or streaming services that are part of your listening repertoire. For me, the ER4XR delivered just the right balance--a clean, detailed, refined sound with the just the right amount of warmth in the midrange and bass. Add in the excellent noise reduction, and these IEMs are great for those times when you're stuck on a crowded train or plane (or just in your own noisy house!) and you want to disappear into a high-quality soundscape ... without having to deal with the bulk of over-the-air headphones. In fact, as I type this, I'm sitting in a very crowded, noisy coffee house, and all I hear is the pleasing sound of my demo tunes playing through the ER4XR (at a moderate listening level, I might add). I intended to listen to music for just a few minutes as I wrote my parting thoughts, but it has now turned into an extended listening session. That seems to happen a lot with the Etymotic ER4XR.

Additional Resources
• Visit the Etymotic website for more product information.
• Check out our Headphones category page to read similar reviews.