• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Radsone Earstudio ES100 Bluetooth DAC & Amp Review

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
22,214
Likes
32,782
Location
Seattle Area
#1
This is a review and detailed measurement of Radson Earstudio ES100 portable Bluetooth, DAC and headphone amplifier. It was kindly sent to me by the company year and half ago and for one reason or the other, has been waiting for this review. :) The ES100 costs US $99 on Amazon including free shipping.

Despite all the functionality and included battery, the ES100 is quite diminutive in size:

Radstone Earstudio ES100 Bluetooth Headphone DAC and Amp Review.jpg

On the flush side that you see, there is a lit ring that changes colors. I am not a fan of such status indicators and have to keep fighting trying to figure what status it was in.

Here are the controls you get:
Radstone Earstudio ES100 Bluetooth Headphone DAC and Amp Controls Review.jpg

What sets the ES100 aside from dongles and such is its app in Android and iOS that gives you very detailed control over operation of it. One very useful feature is setting the amount of power available from either 3.5 mm and 2.5 mm "balanced" headphone connections. That said, one of the settings can cause damage to the device if used incorrectly. I would have wished the device was more resilient that way.

Testing Bluetooth devices is challenging since my analyzer cannot control them directly. Fortunately the ES100 also acts as a USB DAC on Windows. Alas, it only supports 16 bit resolution on Windows whereas it supports 24 bits on Mac. I have not seen such discrepancy in the past and it impacted one of the tests negatively.

I should note that I received exceptional support from the designer when we started our conversation about reviewing the ES100. He seems quite knowledgeable and approachable which is a major plus in my book.

DAC Audio Measurements
All the tests including this dashboard were conducted by using the ES100 on Windows. With phones depending on the software you use and especially with Bluetooth, you may get degraded performance.

Radstone Earstudio ES100 Bluetooth Headphone DAC and Amp Audio Measurements.png


I had to reduce the input level by 4 dB to get the ES100 to not clip resulting in less than optimal 1.1 volt output (for DAC use that is). Phone dongle don't do better anyway so in this market segment, that is not an issue.

SINAD (signal over noise and distortion) was good enough to land in the "GOOD" category of all DACs tested:

Best Bluetooth DACs Tested.png


Intermodulation distortion versus level shows the clipping behavior well:

Radstone Earstudio ES100 Bluetooth Headphone DAC and Amp IMD Audio Measurements.png


Linearity was impacted a lot due to 24 bit to 16 bit truncation (rather than dithered):

Radstone Earstudio ES100 Bluetooth Headphone DAC and Amp Linearity Audio Measurements.png


Headphone Amplifier Audio Measurements
Most important test for headphone amplifiers, especially in this category, is the amount of power they have. Fastest way to get bad sound is for an amplifier to run out of juice and clip. So let's start with 300 ohm load which would represent high impedance headphones and ability of the amplifier to produce high enough voltage:
Radstone Earstudio ES100 Bluetooth Headphone DAC and Amp Power into 300 ohm Audio Measurements.png


The 3.5 mm jack provides a bit more power than competing dongles like Apple USB-C. Where the show gets interesting is using the 2.5mm jack in high mode. There, we get quadruple amount of power which is quite significant. Noise level is higher though so performance with sensitive IEMs may not be good.

Stepping down to 50 ohm load we get:
Radstone Earstudio ES100 Bluetooth Headphone DAC and Amp Power into 50 ohm Audio Measurements.png


I am not sure if the jack is lose or not but I got pretty different results in one channel versus the other (red vs blue) with 3.5 mm output. Power was limited to 23 milliwatts. Switching to 2.5mm in low mode (high mode is not allowed for impedance < 300 ohm), give us more than three times the output which again is significant.

Stepping down even further into 33 ohm load we have:

Radstone Earstudio ES100 Bluetooth Headphone DAC and Amp Power into 33 ohm Audio Measurements.png


I don't have a balanced 33 ohm load so I am showing the two modes for 3.5 mm output. As you see, they almost make no difference even though one is said to have more current than the other.

Putting these in rankings for 300 ohm we get:
Highest Power Portable DAC at 300 ohm.png


All the devices that have more power also use a lot of power and don't have their own batteries as ES100 does.

Here is where we stand in 33 ohm with me estimating the power the ES100 could produce:

Best portable bleutooth dac for phones.png


Listening Tests
I wanted to test the 2.5mm "balanced" output but unfortunately all of my balanced cables terminate in XLR. I bought an adapter to 2.5 mm on Amazon which should be here by the end of the week. So for now, my testing is based on 3.5 mm output.

On both of my test headphones, the Sennheiser HD-650 and Drop Ether CX, there was good amount of output. I suspect these larger devices with batteries included have better peak output than testing indicates. With the increased output of the 2.5 mm, both of these should sing a lot louder and bring with it more impact.

Conclusions
The Earstudio ES100 is a pretty unique offering ranging from its included battery to nice control through its mobile apps. Dongles rely on simplified heuristics to determine available power which easily misfires, underpowering headphones. Not so with ES100. In addition, the ES100's included battery means you are not draining the power out of our mobile device as much as a dongle would.

So overall, I am going to put the ES100 on my recommended list.

--------
As always, questions, comments, corrections, etc. are welcome.

They say you should feed your pets fish to get them to have a shiny coat. So I went on Amazon and they want $35/pound for dried fish for dogs! Even though my panthers don't have any fur, you wouldn't want them to have dry ones, do you? So let's all get together and raise money to buy a few pounds of these fish treats using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
Joined
Apr 4, 2019
Messages
72
Likes
115
#3
What a cool combination of performance,form factor and features. Mine arrives tomorrow!
 
Last edited:

Soniclife

Major Contributor
Patreon Donor
Joined
Apr 13, 2017
Messages
2,020
Likes
1,618
Location
UK
#4
Is there a reason the dynamic range tests are missing?

Looks a promising product, my phone still has a 3.5mm jack, they are disappearing fast sadly.
 
Joined
Aug 15, 2019
Messages
9
Likes
3
Location
Chicago
#5
I am curious about this statement:
Noise level is higher though so performance with sensitive IEMs may not be good.
In my experience, the ES100 (2.5 or 3.5) does not hiss with my Andromeda V1, which hiss with most sources. So at least in my case, I don't have that issue.
 

VintageFlanker

Addicted to Fun and Learning
Patreon Donor
Joined
Sep 20, 2018
Messages
875
Likes
1,440
Location
Paris
#6
I wasn't that impressed by mine (used it with Aptx HD codec) and I didn't keep it.

Seeing this average measured performance, I don't regret anything...

Would be curious to see how it performs against Shanling UP4 and Fiio BTR 5.
 

Jimster480

Major Contributor
Patreon Donor
Joined
Jan 26, 2018
Messages
1,191
Likes
683
Location
Miami
#7
Interesting review.... if it doesn't draw any power from the phone then it would be good for people who do running or biking. To take it on longer trips (maybe if you take the subway to work or something).
Can you measure the dimensions? Its hard to understand the exact scale with just the pink panther :p
 
Joined
Apr 1, 2018
Messages
37
Likes
50
Location
Seattle
#8
@amirm Wow finally! :) I don't know if WS Lee contacted you or not recently but he left Radsone and is started working at a different company making a similar, but improved product:

Well, I resigned my duty as a CTO at Radsone, earlier this year.
And I officially found a new corporation with my colleagues in April this year, named Qudelix, Inc.

Currently, we, Qudelix, are developing a new advanced Bluetooth DAC/AMP with the latest platform and technology including Qualcomm QCC512x, AK4377a and TI OPA1622.
https://www.qudelix.com/5k-dacamp


Now, we're at the design verification phase testing the engineering samples.

The following project schedule would be:
October - Kickstarter campaign
November - Indiegogo campaign
January 2020 - Mass Production & Release


I hope you can check our new project and let us know any feedback or comments, homepage, question, specification whatever they are.

Please check our website for more information and let us know any feedback or comments.
https://www.qudelix.com/5k-dacamp

https://www.facebook.com/qudelix/

This new product looks pretty interesting. I was surprised they went with 2.5mm instead of 4.4mm though.
 

Cahudson42

Active Member
Joined
Sep 21, 2019
Messages
103
Likes
110
#9
Thanks for reviewing, Amirm. A lot of us were waiting for it. Perhaps in future the BTR3 can be reviewed for comparison?

Personally, the es100 ended up not for me. I bought one off Amazon, and returned it just before the return window closed a few weeks ago. To me, it just didn't have enough juice for my HE400i. Listening, say, to Mussorgsky 'Great Gate at Kiev' was flat and lacked a lot of the dynamic range of my desktop D10/Liquid Spark combo. Plus, after Amazon Music HD/UHD came out, and lossless 16/44.1 streaming suddenly got affordable, I decided to try to eliminate bt when possible, so I wasn't needing that capability..

Replaced it with an NX3s when they went back down to $55 on Amazon. But while this is definitely a 'juice' improvement over the es100, even it lacks a noticeable bit compared to D10/LS.. So still looking for a portable/pocketable solution...

Keep up the great work! Without ASR I would never have known enough to get the D10/LS/HE400i - which I am greatly enjoying and see no need to change:)
 
Joined
Oct 5, 2019
Messages
58
Likes
41
#10
Very interesting. Subjective and anecdotal but I was very unimpressed with the ES100 driving my Sony Z1R as it just sounded off. I strongly believe amps and DACs are audibly transparent so I was very surprised at this, and initially thought the Sonys weren’t my cup of tea.

I recently bought a RME ADI-2 DAC (primarily for the multitude of useful features), and was fully expecting no audible difference vs the ES100; it never even factored as a decision point. To my surprise (which persisted for weeks until 10 min ago when I saw this review), the Z1R sounded great out of the RME.

Now subconsciously I could’ve perceived the RME as a higher quality product which in turn positivity influenced my conscious evaluation; can’t rule that out. Another explanation is the distortion of the ES100 is just within the audible threshold, particularly with transparent headphones. How reasonable is that?
 
Joined
Apr 1, 2018
Messages
37
Likes
50
Location
Seattle
#11
Interesting review.... if it doesn't draw any power from the phone then it would be good for people who do running or biking. To take it on longer trips (maybe if you take the subway to work or something).
Can you measure the dimensions? Its hard to understand the exact scale with just the pink panther :p
from their product page on amazon
Dimension 1 x 2 x 0.5 inch / Weight 20g
 

Berwhale

Active Member
Patreon Donor
Joined
Aug 29, 2019
Messages
217
Likes
179
Location
West Sussex, UK
#14
@amirm Thanks for finding the time to test this. You've pretty much confirmed my subjective view of the device (which I use every day with balanced MeeAudio Pinnacle P1 IEMs during my commute). In terms of SQ I find little difference between the the ES100 and the Fiio BTR3 which I also own, however the additional control offered by the Radsone app and the ability to set and store parametric EQ on the device justify the additional cost over the Fiio (even if the build quality of the Fiio is much better).
 
Top Bottom