Earstudio ES100 featured

Earstudio ES100 Bluetooth Receiver – Review

Wireless earphones are cool, right? Well, yes, they are but they also kinda suck. They generally suffer from having inferior audio quality than their wired counterparts and often the battery life is disappointing too.  What if you already have good headphones but your new phone doesn’t have a headphone jack? Meet the Radsone Earstudio ES100.

The Earstudio is a Hi-Res Bluetooth receiver that you can use with any of your existing headphones. But it takes things a step further. Not only can you use any earphones with the Earstudio but you can run them either single-ended or balanced. Oh, and you can use it for hands-free calling too. There’s a lot more as well so let’s get into it.

Radsone website: https://www.radsone.com/earstudio

  • Extremely lightweight and portable
  • Has a good battery life
  • Hands-free calling
  • Very customizable/has loads of configurable options in the app
  • Has good output power
  • Has additional 2.5mm balanced output
  • Value for money
  • The clip doesn’t have much clamping force
  • Button placement not ideal

Buy on:

Buy from Amazon

This sample was provided for the purpose of an honest review. All observations and opinions here are my own, based on my experience with the product.

Testing was done using firmware version 1.3.2

Package and Accessories

The Earstudio’s packaging is really basic but it’s simple and practical. It comes in a small white box with a basic illustration of the device on the front.

Earstudio ES100 box

Inside the box is the Earstudio ES100, a USB to Micro-USB charging cable, a lanyard and a card illustrating the basic operation of the unit.

It’s not the most exciting unboxing experience but as you’ll see later, the value has been added to the device itself and the packaging was kept basic in order to keep the price as low as possible.

Earstudio ES100 accessories

Build Quality and Design

The Earstudio ES100 is a tiny little thing, smaller in size than an average matchbox. The chassis is constructed from a lightweight plastic. It doesn’t feel especially premium but it doesn’t feel cheap either

The front of the device has a matte finish and below its surface lies a single circular LED which flashes in different colours indicating various states of operation.

On the left side of the device is the 3.5mm single ended headphone jack, volume plus and minus buttons and the built-in microphone. The right side has the 2.5mm balanced headphone jack, a multi-function button and the forward and back buttons.

On the bottom is the Micro-USB port which is used for charging the battery or plugging into another device to use in DAC mode. On the top is a small 
through-hole for the supplied lanyard.

Earstudio ES100 clip
The ES100’s handy metal clip

There’s a handy spring-loaded metal clip on the back of the unit for attaching the device to your shirt, jacket, belt or anywhere you like really. It does the job but the clamping force is rather weak so it’s okay for walking about but not for strenuous physical activity. In those situations, I just keep it in a pocket instead.

Earstudio ES100 hand with clip


Now, this is where the Earstudio ES100 really shines. Pairing it with a source is super easy and you can actually pair it with 2 sources simultaneously and easily switch between them. An audio prompt lets you know when the device is powered on or off or successfully paired with a source.

There are a number of high-quality Bluetooth codecs to choose from including aptX, aptX HD, AAC and LDAC. Your preferred codec can be chosen within the Earstudio app.

Speaking of the app, this is another aspect aside from the balanced headphone output where the ES100 sets itself apart from the competition. There are heaps of settings available that you can tweak to your heart’s desire, great for all the control freaks out there.

Don’t worry if you’re not tech savvy or familiar with audiophile lingo. The Earstudio ES100 works perfectly on its own, you don’t even need to install the app if you don’t want to (though I would highly recommend it).

Each setting has very helpful and detailed information explaining exactly what everything does. And there’s no need to worry about messing things up either. You can simply do a factory reset via the app menu.

Things like the 4 digital filter settings of the AK4375a DAC, the level of cross-feed and Radsone’s proprietary Distinctive Clear Technology (DCT) will get any audio nerds neurons firing and all can be manipulated within the Earstudio app.


One of the most popular features of the ES100 is the equalizer. There are 12 presets and 4 custom settings available for the 10 band equalizer. Personally, I never use EQ with any of my gear but I know it’s a mainstay for a lot of people and the Earstudio makes using EQ very simple. There are even plans for a parametric EQ to be added in a future update.

Hands-Free and Ambient Sound

The Earstudio ES100 has a hands-free function allowing you to make phone calls even in your headphones don’t have a microphone. The unit’s built-in microphone can also be used for a nifty feature called Ambient Sound that allows surrounding noise to pass through into your headphones.

This is really useful because if someone is talking to you or there is a public announcement you don’t need to remove your headphones to hear what’s going on around you. You can even set the level of ambient sound you want to mix in and map the function to one of the physical buttons for quick access.


The Earstudio ES100 can be used as an external DAC. It works with Windows, MAC and Linux operating systems. It’s worth noting that the sample rate is restricted to  16-bit 48000 Hz in Windows OS. However, MACos supports 24-bit but I ain’t mad about that! It still sounds great from my Windows PC and is certainly a step up from the onboard audio.

Bluetooth and Battery Life

Bluetooth connectivity is very stable and I’ve never had a problem with cutouts or dropped signal. The maximum range may vary depending on which Bluetooth codec you’re using and to a certain extent will depend on your source’s signal strength.

The ES100 has a rated battery life of 14 hours which is better than what most Bluetooth earphones and a lot of the current DAPs offer. Considering its size, weight and power output this is really impressive.

Earstudio ES100 with Fusion CIEM


Gear used for testing include the Sony NW-ZX300 and Shanling M0 as sources (both LDAC) and my Android smartphone (aptX). IEMs tested include Sennheiser IE 800 S, Custom Art FIBAE 3, RevoNext QT2 and TSMR 7-Star.

At the heart of the Earstudio are two AK4375a DAC/HPAMP ICs and they really do provide an incredible sound, particularly when used in conjunction with a high-quality codec such as aptX HD or LDAC. 

Radsone has some genuine engineering clout and the ES100 has a 1Ω output impedance in single ended and just 0.5Ω from the balanced output. This means that background noise and hiss are minimal, even with very sensitive IEMs. Personally I’ve never once noticed any hiss from the device, although my tinnitus would probably cancel it out anyway.

The ES100 has a rich, detailed sound that is better than I could ever have expected from a Bluetooth receiver/DAC. Streaming music via LDAC from my Sony ZX300 or Shanling M0 the audio quality is extremely close to that of going wired. I was a slow convert to wireless audio but I can’t deny it’s plausibility any longer.


Earstudio ES100 vs Ampio VS-1880 ($189 US)

The VS-1880 is another great Bluetooth receiver/amplifier that I had the chance to test recently. Unlike the ES100, the Ampio has a metal chassis that looks and feels a lot more premium in comparison. It’s also considerably smaller as well.

Just like the ES100, the VS-1880 has hands-free functionality allowing you to make phone calls while using the device. Both devices can be used as external USB DACs and both support aptX HD, LDAC and AAC.

In terms of audio quality, the Ampio performs well. Compared to the Earstudio’s AK4375a, the Ampio uses the DAC function embedded in the Qualcomm CSR8675. The quality doesn’t differ all that much but the ES100 has a higher output power and lower noise floor.

The VS-1880 has a 10-hour battery while the ES100 can go up to 14 hours. The Earstudio comes in at a much more affordable price of $99, while the VS-1880 is $189. Unless you specifically dislike the plastic materials of the ES100, it’s a little difficult to recommend the VS-1880 at almost double the price.

Earstudio ES100 vs FiiO BTR3 ($70 US)

A notable difference between these 2 devices is their build materials. Compared to the plastic of the ES100, the FiiO has a gorgeous aluminium alloy chassis wrapped in 2.5D glass.

Both devices feature hands-free calling and support for high-res Bluetooth codecs although the BTR3 goes a step further by adding aptX-LL (Low Latency).

Audio quality from both units is comparable but the BTR3 sounds just a little bit leaner and more transparent. The ES100 has superior output power making it more suitable for harder to drive IEMs and headphones.

At the time of writing there is no app support for the BTR3 but they are supposedly working on it and will add a battery indicator,  an EQ plus 4 audio filters available.

The ES100 clearly has more features and customization options than the BTR3 which will appeal to certain power users. At the same time, some will feel more comfortable with the more straightforward operation of the BTR3.

Both devices offer great value. At $99 the ES100 has its app features plus the 2.5mm balanced output while the BTR3 boasts a superior build quality and a lower price of $70.

Earstudio ES100 with Sennheiser IE 800 S


The Earstudio ES100 is an incredibly versatile and appealing gadget. Things like the balanced headphone output and the vast amount of settings customization are just what many audio enthusiasts have been waiting for in a Bluetooth device.

And it hasn’t even reached its full potential yet. Radsone really listens to their customers and continue to provide updates for firmware and the app software, so there is even more functionality and features to come in the future.

This has become one of my absolute favourite gadgets and if you’re looking for a Bluetooth solution then the Earstudio ES100 is at the top of its class.