Etymotic ER4XR-BT Review: The Best With Bluetooth

Almost 4-years ago to the day, Mark reviewed the critically acclaimed ER4XR IEMs from Etymotic, and drew a similar conclusion. These were the crème de la crème and Mark’s conclusion summed it up; “If the world could only have 1 IEM in existence, this should be the one”. Etymotic has now released a combination of their class-leading IEMs with a Bluetooth module built in-line, in the ER4XR-BT unit. This is going to be fun…

Etymotic ER4XR-BT
  • Simply the best I've tested
  • Good battery life
  • Excellent accessories list
  • Still a pricey piece of tech
  • Bluetooth module is bulky

Buy on Amazon – £399


The ER4XR-BT IEMs were provided free of charge in exchange for a full and fair review. Etymotic have requested no specific treatment, and nor will they have input into the content of this review of early-access to the final published article. The ER4XR-BT has been tested over a one week period whilst paired with an Android smartphone and a Dell laptop.

Quick Links…


Etymotic knows how to deliver good sounding audio; they’ve been researching audio for over 30-years. Last year we, or more specifically Mark, reviewed the ER4XR. The ER4XR was a slightly more bass-tuned version of the studio reference ER4SR release. These ER4XR-BT units are essentially the same amazing Extended Response IEMs but with the Bluetooth cable, addition to free you from wires. For purists, this may well be a slight against all that is holy in the audiophile world. If you have IEMs such as these, you should really be looking to use accompanying high-performance cables to connect up to your systems, right? It’s 2020, I think all rules have been broken and clearly, Etymotic agrees.

As you can see in the unboxing, the packaging the ER4XR-BT arrive in is premium. The offset slide design has the ER4XR-BT front and centre, with the IEMs already connected to the Bluetooth cable via the standard MMCX connection.


The ER4XR-BT has a balanced armature driver design. I’ll snip what I said in my ER2XR review from April 2019 in relation to armature drivers, below for reference.

A quick lesson is required – you have to sit through it because I did! Balanced armature drivers have a fundamentally different construction to that of dynamic drivers. In a balanced armature driver, the armature (the moving bit) is surrounded by a stationary coil and is suspended (balanced) between two magnets. Once the electric current is passed through the surrounding coil, the magnets engage the armature causing it to agitate. This movement drives a diaphragm which causes the sound.

Cable & Controls

Along the right cable length (as presented) sits the control pod; a short plastic cylinder on the ER4XR-BT which controls play/pause and volume controls. There’s no dual functionality of these buttons, they just do what they say they are going to do. Having said that the play/pause button does serve to accept/end a phone call also. They are clicky and satisfying but aren’t differentiated from one another in texture. Further down the cable, we hit the Bluetooth control box. Again, a slab of black plastic is this time adorned with the Etymotic logo and a micro USB charging port.


Specs & Box contents

  • Balanced Armature Drivers
  • High 122 dB SPL Sensitivity
  • 35 to 42 dB of Noise Isolation
  • Built-In DAC & Headphone Amplifier
  • 24-Bit/48 kHz Lossless Playback
  • MMCX Earbud Connectors
  • Over 8 Hours of Playback
  • Built-In Microphone for Hands-Free Calls
  • In-Line 3-Button Playback/Call Controls
  • Awareness Mode to Hear Surroundings

In The Box

  • 3 sizes of triple-flange tips
  • 2 sizes of foam tips
  • 4 sizes of dual-flange tips
  • Filter removal tool
  • Shirt clips
  • Small IEM carry pouch
  • Larger accessories carry pouch
  • micro USB charging cable

Performance & Use

These are heavenly to listen to. I understand what Mark was getting at in his review. They are so incredibly balanced. Before all of that though, how do they feel and sit in the ear?

In my testing, I used the triple-flange and foam tips included with the unit. As expected, the triple-flange tips felt like I was undergoing some form of surgery. They sit very deep in the ear canal and I was honestly fearful of causing myself harm! I need not have worried. As soon as I started listening to music, not only did I start to forget I was even wearing them due to the isolation, but they rarely moved. That lack of movement provided me with comfort! The foam tips can be tried also for adding an increased level of insulation from the outside world. A note of caution; I would urge anybody using these on a commute to be careful. They do block out quite a lot of noise. Just don’t cross roads blindly with these in – you might not hear that bus!


I’m no audiophile so take this with a pinch of salt, but the lows, mids and highs are all amazing. Listening to some of my favourite acoustic songs on these ER4XR-BT IEMs was a very emotional experience. I probably expected more bass than was present in most scenarios, simply due to the XR rating of this device. What caught me out is just how balanced everything is. I’m used to testing headphones that are tuned specifically for a bass-heavy response. The ER4XR-BT is also, but just not to the same extent. Nothing is over-powered. Everything is balanced, as it should be (insert Thanos GIF here).

When I switched out the flange tips for the foam tips I noticed a subtle shift in tone. The bass was a little more prominent. Nothing earth-shattering but an obvious shift. The lows reached the same level of importance that I’d heard in the ER2XR testing period, but this time with more clarity and detail throughout.

I managed to get just over 7-hours of playback in my torture test, and for the first 2.5-hours of that, the ER4XR-BT was sitting in my ears. I felt no fatigue, no discomfort, no pain – just bliss!


The Only Blot On The Copybook

It’s not quite perfect though. I do have a few niggles. In 2020, relying on a bunch of plastic clips to anchor a bulky, and incredibly cheap feeling, plastic Bluetooth module is far from premium. It’s clear that Etymotic is used to delivering audiophile-grade (read, not Bluetooth) technology, as the Bluetooth module just feels stuck on. It is supposed to be seated behind your neck during use. Whilst I’m aware these aren’t supposed to be used at the gym, or in anywhere else but sitting relaxing and enjoying the music flowing through them, it still feels a little bit of an afterthought.

My final irk is slightly less of an issue, but micro USB, in 2020? Come on Etymotic.

Final Thoughts


These are amazing. Amazing audio, amazing design – amazing. What might be slightly less amazing depending on your point of view, is the price. It’s not that they aren’t worthy of the £399 price due to the inclusion of the Bluetooth module, as they most certainly are. These are at top of a shortlist of the best IEMs – period. Due to that, they demand to sit front and centre in the pantheon of pricey IEMs and they do. No, the issue is that there is a niche market for this ER4XR-BT unit. That niche is the wealthy or audio professional. Thankfully both categories wouldn’t think twice of dropping that sort of cash on a device this good.

The ER4XR-BT has enough low-end for me, even as somebody who enjoys their Hip-Hop as much as I do, and the rest of the soundstage delivers an extremely detailed response.

If you can afford them, this package is unmissable – if nothing else, you must get to listen to these.

About Craig Bradshaw

Tech enthusiast and Editor-in-Chief of MobileTechTalk

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