Earstudio ES100 MK2 Wireless Headphone Amplifier and DAC Reviewed

Published On: April 1, 2020
Last Updated on: October 31, 2020
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Earstudio ES100 MK2 Wireless Headphone Amplifier and DAC Reviewed

In many ways, the Earstudio ES100 MK2 ($99) appears similar in function to the Bluewave Get we reviewed just over a year ago. The ES100 MK2 measures just two inches tall, an inch wide, and half an inch thick, and...

Earstudio ES100 MK2 Wireless Headphone Amplifier and DAC Reviewed

  • Brian Kahn is the longest tenured writer on staff at HomeTheaterReview.com. His specialties include everything from speakers to whole-home audio systems to high-end audiophile and home theater gear, as well as room acoustics. By day, Brian is a partner at a West Los Angeles law firm.

In many ways, the Earstudio ES100 MK2 ($99) appears similar in function to the Bluewave Get we reviewed just over a year ago. The ES100 MK2 measures just two inches tall, an inch wide, and half an inch thick, and weighs in at just under an ounce and a half. The front of the device is a clean black panel with a flush, circular LED status light near the bottom.

61DqATxRSUL._SL1190_.jpgThe sides, top, and bottom panels appear as one silver band with rounded corners. The left side has a 3.5mm headphone jack above an up/down rocker switch, with a microphone behind a small pattern of holes toward the bottom of the side panel. The right side has a forward/back rocker switch right under a small round play/pause button.

It is the 2.5mm balanced audio headphone port above that button that hints at the ES100 MK2's more advanced audio capabilities. A large, wide, spring-loaded clip dominates the rear of the unit, pointing to its portability. Lastly, a micro-USB port can be found on the bottom surface. This port can be used as USB DAC input or to charge the unit, although the 14-hour battery life gives you lots of time in between charges.

The ES100 MK2 is Bluetooth 5.0 compatible and supports the following transmission codecs: AAC, AptX, AptX -HD, LDAC, and SBC. It can receive up to 24-bit signals via Bluetooth but only 48kHz/16-bit via USB. Two AK4375a DAC/HPAMPs are utilized, one for each channel, and they feed an analog volume control to avoid loss of resolution when lowering the volume. The ES100 has a companion Android/iOS app that provides control of a large number of features and audio adjustments, including, but definitely not limited to: codec mode, output selection, battery level, analog and digital volume control, EQ, and several more audio control functions.

71YNN7lPgfL._SL1187_.jpgOne of my favorites is Ambient mode, which pipes in sound from the ES100's microphone. I like to use this when I'm out in public so my closed back, over-ear headphones don't completely isolate me from what's going on around me. It is much safer to hear something coming your way before it reaches you.

Some other interesting features include DualDrive and Car Mode, the latter of which lets you connect the ES100 to your car and has it automatically power up and down. DualDrive improves audio performance with hard-to-drive headphones by doubling the current or voltage, depending on whether the balanced or unbalanced output is being used. While the packaging and documentation is extremely lacking, the Radsone website has a detailed user manual and several white papers providing more detail on the ES100's features.

In order to do an "apples to apples" comparison with the previously reviewed Bluewave Get, I did most of my listening with the same headphones and some of the same music. These headphones included Ultimate Ear's Reference Remastered, Etymotic's ER4XRs, Audeze LCD-XCs, and MrSpeakers' Aeon Flow (closed back) headphones. I used my iPhone XS as the source, alternating between being connected to the iPhone wirelessly and a wired connection with the Apple Lightning to 3.5mm adapter. I also briefly tried the ES100 as a USB DAC with my Microsoft Surface running Windows 10.

I started my listening with Imagine Dragons' album Evolve (Interscope, Tidal). The ES100 was much better than the iPhone XR's headphone output in every way, on every track. On "Thunder," bass was reproduced with significantly more solidity, extension, and detail via the ES100. The ES100's articulation was particularly evident with harder-to-drive headphones, with which my iPhone and iPad sounded quite muddled in comparison. In comparisons with my iOS devices, the ES100's soundstage reproduction was more natural in overall placement with the individual instruments and vocals more solidly placed.

Imagine Dragons - Thunder

I spent a few hours listening to a variety of tracks across a variety of genres through Tidal and Qobuz. The ES100 MK2 did an admirable job of reproducing more texture and detail with stringed instruments and bass notes, a marked improvement over my phone, tablet, or computer. One of the last songs I listened to was Halsey's "Ashley," from her album Manic (Tidal, Capital Records), as I wanted to take a close listen to a track with female vocals. I used the Etymotic ER4 XR and MrSpeakers Aeon Flows for this track. I started with the Aeon Flows and immediately noticed that Halsey's voice imaged well, with solid presence. The synthesized instruments were positioned in my head, arrayed behind Halsey's vocals and with taught and deep bass.

High Points

  • The ES100 MK2 provides you with the option of both balanced and unbalanced outputs, which provide enough clean power to drive most popular audiophile headphones.
  • The sound quality is significantly better than what I was able to obtain with the same headphones wired directly to an iPhone, iPad, or computer.
  • The Earstudio app provides a lot of functionality and control when applied judiciously.

Low Points

  • I did not care much for the physical chassis of the ES100 MK2. While it held up fine during testing, it felt like an inexpensive product, leaving me with questions about its long-term durability. The button layout, with buttons on both side of the body directly across form each other, also made it too easy to accidently press the wrong button.
  • The included documentation and packaging are subpar for an audiophile product, even at this price point. The device was loose, in a small, relatively flimsy cardboard box with only a quick start sheet, which did not reference the website or Earstudio app.

Competition and Comparison

The Bluewave Get ($129) is similar in form and function. I like the build quality, controls, and feel of the Get more than the ES100 but the ES100's app provides it with much more functionality.

Audioquest's DragonFly Black, Red, and Cobalt ($99, $199, and $299, respectively) are probably the best known of the tiny USB DACs. These units put out 1.2 or 2.1 volts depending on the model, and have different ESS Sabre DACs, so you can choose the model that best suits the power needs of your headphones. However, the Dragonfly DACs do not have Bluetooth capabilities.


The Earstudio ES100MK2 pleasantly surprised me. Its amplifier was able to drive the majority of my headphones pretty well. Hooking up my Audeze LCD-XCs to an iPhone usually does not work very well, whereas the ES100 MK2 did a fairly good job of driving them to satisfying listening levels. In comparison with the Get, I found the ES100 MK2 to provide greater control and detail with a larger number of headphones

The customization made available through the companion app also allows the user to adjust the sound to their personal tastes, although one has to exercise restraint not to go overboard with the processing options.

The ES100 MK2 also provides other features may be important for some users. The micro-USB DAC is par for the course for this product class, but the car mode implementation can be helpful for those looking to tie into a car audio system.

All in all, the ES100 MK2 provides sound quality that punches way above its weight class, both figuratively and literally. The sound quality, coupled with an incredible amount of customizable functionality at a bargain price, makes this a very easy product to recommend to a listener that is looking to step up their portable audio experience.

Additional Resources
• Visit the Earstudio website for more product information.
• Check out our Headphone + Accessory category page to read similar reviews.
• Read HomeTheaterReview's Wireless Over-Ear Headphone Buyer's Guide.

  • rutstygh
    2022-04-25 09:13:35

    When you list Audioquest's DragonFly Black, Red, and Cobalt, as Competition and Comparison. I really step back and wonder about everything you just reviewed? Those are not competition or comparison, and by listing them as so, it seems you have forgotten the best feature of the Earstudio es100 mk2.

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