Radsone ES100 - Bluetooth DAC/Amp - Official Thread


I’m considering a Bluetooth DAC/Amp like the ES100 and the FiiO BTR series. Any advice on the choices here?

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I can’t give you any advice on them at the moment … but based on the question I just ordered the ES100 and the BTR3 so I can compare them. It’d be nice to have a compact, LDAC-compliant, Bluetooth adapter for use on the go …

Nominally I am inclined to suspect the FiiO will have better performance, which is based on nothing more than actually having heard of them. But the balanced-drive capability of the ES100 is intriguing enough to make it worth checking out.

I suspect output power will be the deal killer with these units … very likely more than ample for IEMs, and probably not nearly where I’d want it for anything else, but we’ll see …


I’ve owned the ES100 and the BTR1. I still have the ES100. :slight_smile:

The ES100 is easily my recommendation, though the new Fiio ones do have similar feature-set.

That said, the ES100 for me is wonderful. It has balanced and unbalanced connections, every BT codec, and works as a USB DAC if needed. The app is really well designed and full-featured including Equalizer and Crossfeed editing , and has enough power to use my hungriest headphones on balanced.

It’s a huge surprise from a pretty much no-name company. It also sounds very nice. The company has also been extremely receptive to feedback and criticism and have made every effort to update their firmware and app to requests.

I wrote a very schilling review here: https://www.antdroid.net/2018/09/radsone-earstudio-es100-little.html

But it’s because I think this little gem is worth every penny.


I’ve read that the ES100 can drive up to 600 ohms while the FiiO is limited to 100.


Another neat Bluetooth toy to consider is the TRN BT20. These are for detachable IEMs. They lack AptX and LDAC support but they do have AAC support IIRC. The big benefit for these is that they are fully wireless and have very long battery life to boot. I’ve been quite happy with these as well for walking around and doing work around the house while using my IEMs.

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The interesting question there is how much power is available for a given load.

Some digging reveals that the FiiO BTR3 can deliver 33mw into 16 ohms, and the ES100 can do 40mw into 16 ohms (single ended) and 160mw into 16 ohms (balanced). That latter figure doesn’t make much sense, but the ES100 is clearly more powerful.

Which means that, personally, I wouldn’t pair either one of them with anything at 300 ohms, let alone 600. But that’s me.


Radsone has published a lot of interesting papers on their amp design and their patents. It’s their data though, so you have to take it with whatever grain of salt is needed.


They also published lab results between the BTR3 and the ES100


I’m having trouble making sense of their numbers. Into a 300 ohm load, they claim max power of 129mW at 1 Vrms. Problem is, 1V into 300 ohm dissipates only about 4mW, so something doesn’t seem to add up.


I PM’d WS Lee from Radsone and got this response:


Thanks for your kind feedback.
As you pointed out,
we’ve found the error in the document that the absolute output power to 300-ohm load has been calculated with 8-ohm load reference.
Please ignore and output power reference in the document.
However, the other values including the output voltage and THD+N are all good and correct.
The document is to provide the comparison result between BTR3 and ES100.
We’ve been requested from many users for the comparison and found that BTR3 has the most common design flaw.
We’ll revise the document shortly.
Thanks once again for point out the error.
Happy new year!

Best Regards,


That explains it! So in practice this would top out at little below 105dB SPL on an HD650.


latest ES100 app update just added more EQ displays/options like Q factor settings and 48Khz USB option.


The ES100 is like a Tesla. It keeps getting better with each update.

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Flash sale $74.25 on amazon.

Expires at around 8PM PST

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No qualms about the sound so far …

But this is a fussy little bleeda’ in every other respect.

Am I missing something, or do you need to power it up and use its companion app to figure it’s charge level?

Doesn’t seem to like any USB cable other than the very short one in it’s tiny box, either.


On Android phones, you can also check battery via Settings -> Bluetooth Devices.

But, yes there’s no display for battery life. It’s sort of meant to be used with your phone, so i think the expectation is you have your phone/app with you. IIRC the LED turns red when you’re low.

Yea, it only comes with the small USB cable. I dont think I’ve ever used that cable ever. I don’t even know where it is to be honest.


It’s a bit wayward in its reporting of charge level - at least via the iOS app.

Even with it just powered on, not playing, and sitting charging, it has jumped around by increments/decrements of 15% or so, for several minutes, before actually settling down.

Turning it OFF doesn’t seem very reliable either. It appears to power down, but sometimes just reboots and then sits silently running down its battery. There are myriad options in the app for this behavior, so it may just be getting the right setting (I’m not sure the actual descriptions of what each option does are necessarily helpful).

This is on the latest firmware, incidentally.

Much more variance in quality between different codecs than I am used to with other devices that support a similar range of options (not sure if this is good or bad yet).


I dont think I’ve had the issues you’re stating with turning it off. It will reboot if you plug it in though. I think it’s an option now in the app to stop that behavior but I havent used mine in a little while.

As far as codecs go, I do feel the quality is discernible between the various options with LDAC sounding the best of the available ones followed by AptX HD, AAC/AptX Tie and SBC.


I was turning it off, then unplugging it from the charger. Which made it reboot and power-on again. If I unplug it and then turn it off, it stays off. Odd behavior, though apparently normal.

An option (and a default one at that) that just says “Don’t change power-on states without me pressing the bloody button” would be nice, rather than having to decipher what it’s going to do in each of its charge mode settings.

After letting it full discharge and then recharging it a couple of times it has gotten a bit more consistent in how it reports its charge level as well. Though you can have it show “Charging Complete 100%”, unplug it, and 10 seconds later it reports “95%”. And then you power it off, turn it on again, and then it claims 98%. Which is not very consistent.

The feature set and configurability is quite impressive. At the same time it reminds me of so many Linux and Android apps that have configuration options out the wazoo, half of which you discover accidentally, some of which don’t necessarily make any sense until you play with them at some length, and several of which lack polish to the point that it makes you wonder if it is working properly at all.

Which makes it fine for someone like me, but largely unsuitable for my wife (no way she’d go playing around in the app to figure out the charging weirdness, so it’d likely wind up never properly charged when she reached for it).

On the codec performance … I’ve certainly experienced differences between the various options with other gear. And I’d agree about their relative merit/performance. I was just surprised at how big a difference there was between them on this unit in particular. Usually it’s a lot more subtle, especially between AAC/aptX and aptx HD.

In this case, the comment was prompted as I was trying out AAC out of curiosity (I bought it for it’s LDAC capability) and it sounded awful. Far far worse than I’ve ever heard AAC sound before. Must have been an environmental or connection issue, or some other transient factor though, as it sounds perfectly fine via AAC today (pretty good, an indistinguishable vs aptX). And unless it does the same thing again, which would start to make me think it could be a software/initialization issue, it’s a non-issue.


On the software side, I agree, it’s a bit of a tech nerd toy. Most of these features we’re implemented due to user input and requests so I imagine they just slapped it together to get it out. And they’ve made a lot of additions since the time it first showed up. The interface actually has changed a bit since then.

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It’s going to require a bit more investigation … especially given the 14-trillion configuration options this thing has, but my first pass at measurements on this thing are, well, concerning (even when immediately compared to properly-correlated re-measurements of other units, for reference).

Jitter, alone, inferred (pure 12 kHz tone @ 48 kHz) or J-Test, just as a USB-DAC is, well, a cluster. I think the only thing I’ve ever measured that was worse was the Audio-GD Singularity S19 (which still holds the record as the absolute worst-sounding DAC I’ve ever encountered). Haven’t gotten to measure this via Bluetooth yet …

Curiously I think the ES100 actually sounds pretty good. I like it. As a whole. A lot. No regrets about buying it.

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