Ichos

Reviewer at hxosplus
Great entry level balanced headphone stack
Pros: + Transparent yet musical sound signature
+ Quite natural timbre
+ Great technicalities for the price
+ Dead silent
+ Fully balanced design
+ The DO100 can be used as balanced preamplifier
+ Powerful headphone amplifier
+ Internal power supply
+ Full size XLR plugs
+ Excellent build quality
+ DO100 comes with a remote control
+ Compact sized
Cons: - Not the most refined or resolving
- Slight traces of digital glare
- No MQA decoding
- No fixed line output for the D0100
- The HO100 lacks preamplifier outputs
The review samples were kindly provided by Aoshida Audio free of charge in exchange for my honest and subjective evaluation.
I haven't received monetary or any other kind of compensation and I don't use affiliate links.
The prices are $239 for the DO100 and $149 for the HO100.
You can buy them from Aoshida Audio here HO100 and here DO100.

SMSL

Well, SMSL needs no introduction, founded in 2009 are specialized in the audio DAC, stereo headphone amplifier and power amplifiers with a very competitive prices.
They pay close attention to user feedback in order to continue improving on their products.

Aoshida Audio

Aoshida-audio is one of leading Platforms which specializes in providing Audio Products, such as: Amplifier, Decoder, Player, Headphone,Cable and Accessories with high quality etc.
All products sold are original and covered by 50-day returns.
They are also part of the World Wide Hearing organization so a portion of every headphone sale goes toward helping a child hear.

SMSL and Aoshida Audio

SMSL DO/HO/AO series is a collaboration between SMSL and Aoshida Audio to build quality products with high value to performance ratio and specifications set by Aoshida Audio as they were collected by extensive user feedback.
The series was inaugurated with the DO200 DAC (review), the HO200 headphone amplifier (review) and the AO200 integrated speaker amplifier (review).
The series now continues with the more affordable AO100, DO100 and HO100.

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SMSL - DO100

The DO100 is a high resolution audio DAC with a compact size suitable for desktop use in the most cramped spaces.
Measuring 150x128x39mm is just slightly larger than the SU-6 and considerably more compact than the DO200.
Despite the compact size, SMSL was still able to squeeze two pieces of the ESS ES9038Q2M chip, in a balanced configuration with regular XLR analogue outputs, pretty impressive for such a mini sized device.
The digital receiver is a 2nd generation XMOS solution that supports DoP256 and native DSD512 and PCM up to 32bit/768kHz.
A separate audio clock processing circuit is used to greatly reduce the jitter.
The user can choose between the seven available low pass filters to tailor the sound to his liking.
All input ports (except Bluetooth) support DSD transmission, coaxial and optical supports DoP64.
Four high-end dual op amp OPA1612 and a large number of audio grade components are used in the digital and analog sections.
What is great about SMSL is that they don't use external power adapters even in their most compact devices.
The DO100 is not an exception since a built-in, discrete component, switching power supply is to be found featuring multiple low-noise power supplies for the analog circuits.
Wireless Bluetooth is also included through a Qualcomm latest chip that supports LDAC 24bit/96kHz, aptX, aptX HD, SBC and AAC.
Digital inputs include USB OTG type-C, coaxial and optical while stereo analogue signal is delivered through XLR balanced and RCA unbalanced outputs.
Both line outputs are variable so the DO100 can be used as a preamplifier to drive active monitors.
Unfortunately you can't configure the line outputs as fixed and you have to use the maximum volume for a full scale level output.
The DO100 features a small, white LCD display which displays sampling rate and other useful information.
A multifunction aluminium knob is located at the right side and is used to control the volume and navigate through the menus.
Of course there is also a full-function remote control.
The unit comes ready to boot as it includes a Bluetooth antenna, a USB cable and an AC power cable.

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SMSL - HO100

The HO100 is the headphone amplifier that stacks together with the DO100 to make for an affordable fully balanced headphone setup.
It has the exact same size and appearance as the DO100 so you can put the one on top of the other to save some space.
The HO100 is slightly more expensive than the budget friendly SH-6 ($120) but in exchange it adds a fully balanced design from input to output.
The amplifier features the SMSL patented technology that is named Ultra-low distortion precision feedback circuit with a distortion as low as 0.00006%.
A high precision low temperature drift resistance technology is used so the performance is not affected by temperature fluctuations.
High quality relays are used for a popless sound design and additionally the amplifier has comprehensive protection such as overvoltage and thermal protection.
The unit has a built-in, discrete component, switching power supply with multiple low-noise power supplies for all the critical parts of the circuit.
The amplifier is very powerful, it can do 3WPC into 16Ω and 1.5WPC into 32Ω from the balanced output with an output impedance near zero.
There are three gain settings high , middle and low, that can be selected from a toggle switch to meet the needs of different headphones.
The interface is pretty simple, you get full sized balanced XLR and single ended RCA inputs at the back but no preamplifier outputs.
The front face sports two headphone outputs, one balanced 4.4mm and one unbalanced 6.35mm.
A 3.5mm adapter is not included.
One switch toggles the input between XLR and RCA, the other is for gain selection and another is for powering ON and OFF.
An aluminum knob is for adjusting the volume, the potentiometer has a smooth and even rotation.
A slight channel imbalance can be heard in the lowest setting of the volume.

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Build quality and appearance

The appearance is neat and minimalist, simple yet very stylish and modern looking.
Both units have a matte black finish and their chassis is made from thick CNC machined aluminium with a luxurious glass panel at the front face.
Both units might be affordable but they don't feel cheap, they have top notch craftsmanship and great looks reminiscent of more expensive products.

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Listening impressions

The stack


Most of the listening was done with both units combined together as a stack but I have also hooked the DO100 to the HO200 and HO100 to the DO200 in order to check individual performance.
The units were burned for about 100 hours before listening tests.
I have mostly used headphones of the same price tag such as Sennheiser HD660S and HiFiMan Sundara but also included in the mix the Focal Clear Mg, Elex and a couple of IEMs to check the noise floor.
Speaking of noise floor, the system is simply dead silent with the blackest background you can possibly imagine making it the perfect companion for sensitive earphones.

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The overall sound signature is balanced and linear with great transparency and tonal accuracy.
Fortunately this is not the bright, over - sharpened sound that is usually associated with budget Chi-Fi products of previous generations.
The sound is just a touch forward but not aggressive nor clinical or boring and in no way harsh or fatiguing.
Regular readers will probably know that I am quite fond of the ES9038Q2M because when properly implemented, it can sound enjoyable and realistic without sacrificing too much in technicalities compared to the grand ES9038PRO.
And such is the case here as the DO100 is musical sounding while maintaining the famous ESS transparency and precision.
The DAC stays true to the source material without any coloring from its part while the HO100 handles the amplification duties without tonal shifts.
The amplifier retains the same levels of transparency and linearity while it does a good job by adding the thrust and dynamics that are necessary for the sound to become realistic.
The experience can be as enjoyable and engaging as your headphones can be, this is the kind of audio gear that is not intervening so the transducers are the ones who will sculpt the final audio shape.
This is not a set recommended for manipulating the sound color in order to compensate for possible headphone deficiencies so make sure that you are going to use your favorite ones.
The texture is not too dry nor too lush while harmonics are presented with adequate saturation and intensity.
Timbre is satisfyingly natural, the stack doesn't sound fake or artificial while digital glare is kept under control, you can only hear a minor edginess and metallic hue in the upper parts of the spectrum.
Technicalities are very good for such a modestly priced set, there is plenty of extension but while detail retrieval is absolutely stellar there is a lack in overall refinement and resolution.
On more practical stuff, bass is controlled, tight and layered with good dynamic range.
The stack is fast, agile with a pacing that stays steady even when things start to become really busy.
Frequency cohesion is excellent, all parts sound blended but at the same time each one stays clearly distinguishable by its unique articulation.
Soundstage is remarkably extended and holographic, especially when utilizing the fully balanced signal path.
Instrumental separation is clear, positioning accuracy is satisfying and so is the ability of the system in communicating the ambience of the recording venue.
As a whole, the SMSL stack proved an excellent performer, easily adaptable to all kinds of music from electronic to classical.
With the Focal Clear Mg, listening to this new complete recording of all Beethoven's piano concertos was an immersive experience.

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The individuals

As good as they sound as a stack, both components can perfectly stand on their own without the slightest giveaway in sonic performance.
The DO100 is an excellent entry level DAC with a musical and precise sound reproduction that can also drive powered monitors.
And the HO100 is a great balanced headphone amplifier with plenty of power, excellent transparency and great dynamic range, missing only the preamplifier outputs.
Both are very competitively priced and can be used as single units to complement or upgrade an already existing system.

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Bluetooth performance

Nothing much to add here than the usual lack of ultimate fidelity especially in the treble.
The Bluetooth implementation is really good and the ease of use can make up for the slight loss of sound quality.
Given that, the DO100 is better from the wired inputs and should be used as such when possible.

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Compared to the rest of the family

Things are pretty simple, pricing honesty and scaling are the plain characteristics of the family.
The SU-6/SH-6 is a great entry level stack for all people who would like to experience good sound for less money.
Then you spend a little more for the DO100/HO100 stack and you get a little more of everything but only if you have balanced headphones, otherwise don't bother.
You gain in transparency, resolution, extension, dynamics, instrumental separation and positioning, holography and overall technicalities with the same kind of sound signature.
And if you can afford it, then you aim for the DO200/HO200 system which sports dual ES9068AS chips that can do full MQA decoding and the amplifier is much more powerful plus it has preamplifier outputs.
Sound-wise, you gain even more of everything reaching for a higher level of sound quality given that you own an equally good set of headphones.
A very honest price to performance ratio and scaling, you get exactly what you paid for, so kudos to SMSL for respecting your hard earned cash.

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In the end

The SMSL DO100 and HO100 both combined or as separate units, are entry level balanced audio devices with great sound and excellent price to performance ratio.
They are well built and despite the compact size, they come with full sized XLR plugs.
The actual value is unbeatable so if you are looking to step into a fully balanced headphone system then look no further, the SMSL stack has you covered both in sound and build quality without breaking the bank.

Test playlist

Copyright - Petros Laskis 2022.
Last edited:

rev92

Reviewer at Ear Fidelity
SMSL DO100
Pros: Value
Incredibly clean, neutral sounding
Very good technical performance
Balanced
Build quality and form factor
USB-C
There's HO100 to stack it with
Cons: Non for the price

Introduction​

I usually start my reviews by introducing the manufacturer of the product I’m currently reviewing, but come on, you know SMSL. One of the leading manufacturers of DACs and amplifiers for years now, offering an extraordinary value and one of the best measuring devices in the world of audio.
So, straight to the point, the hero of today’s review, the DO100. This is a pretty affordable DAC coming at $239. No MQA support, no pre-amp, just a DAC that is focused purely on good audio performance. With its CNC-machined aluminum case, balanced output and Bluetooth 5.0 with LDAC on board it seems like a fantastic entry-level DAC for just about everybody.
We’re pretty much used to SMSL stuff sounding as neutral as it gets. They’re just pushing the prices of their devices lower and lower, delivering better performance. Let’s see how it went this time.

Packaging​

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The unboxing experience of the DO100 is pretty straightforward. It comes in a minimalistic white box with a clean graphic of the DAC on the top lid. Inside you’ll find the DAC, a USB cable (more later), a power chord and a remote.
There’s nothing else to say about it . The quality of included cables is just decent, and the remote has the most important functions like turning the device on/off, changing the volume, muting the device, etc.

Design, Build and I/O​

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The DO100 is made of CNC machined aluminum and it feels pretty solid. It’s a rather small DAC, but it feels substantial and dense in hand. The size feels just about perfect for any desk scenario.

The actual build quality is pretty good, there are no sharp edges, it stays in place thanks to the rubber feet, and looks just great paired with the HO100 amplifier. It has a built-in screen that shows the selected input and the quality of the file currently playing. Lastly, there’s a knob to select the input on the front panel. This is a pretty simple DAC that focuses on only the most important aspects.
From the design point of view, this is yet another SMSL DAC. It’s black, minimalistic, and just an aesthetically pleasing device. Nothing to write a book about, but certainly nothing to criticize. I somewhat miss the times when different DACs really looked different, but I actually understand this kind of approach. This design has been here for years, it’s safe and just good.

Let’s talk about the I/O, and I’m going to start by saying that – SMSL, BRAVO. This DAC doesn’t have a USB-B input, but a USB-C one. Finally, the audio market is entering the year 2018. Jokes aside, this should be a thing for years now and I’m glad SMSL went this way. I can finally plug a DAC into my MacBook without any adapters, just a single USB-C to USB-C cable. This is so good.
Other than the USB, we’ve also got a COAX and Optical input to connect to an external CD transport or a TV, and an antenna screw (of course, the Bluetooth antenna is included in the box to screw in). On the output side, you’ll find both XLR and RCA, so this DAC is pretty universal when it comes to pairing with different amplifiers.
Lastly, the DO100 has a built-in ultra-low-noise power supply, so say goodbye to chunky power supplies laying around on the floor. All you need is just a simple power cord and you’re ready to go. To see a quality power supply in a device this small, with all its features is pretty impressive, to say the least.

Tech​

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Let’s talk tech for a second. First up, the DO100 is built around a dual ES9038Q2M DAC chip, and it used four OPA1612 OP-AMPS.
The Bluetooth chip used is the Qualcomm QCC5125, and it supports LDAC 24bit/96kHz, APTX/HD, SBC and AAC, so when it comes to Bluetooth codes for audio, you’re pretty much set.
The DO100 can decode DSD512 natively and it supports PCM up to 32bit/768kHz.
This combination of different components gives you all you need when it comes to connectivity and different quality of music files. It does not support MQA, so Tidal users should have this in mind (no, I’m not going to comment on the whole MQA situation).
When it comes to the measurements, I’m not measuring stuff myself, but I’m pretty sure you’ll find them online somewhere. I’m pretty sure this will measure as good as it gets, it’s an SMSL DAC.

Sound​

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Okay, okay, you’re not willing to spend a lot, but you still want ultra-high-quality audio don’t you? So, how does the DO100 sound? Well…it sounds incredibly clean and neutral, as neutral as it gets actually. SMSL has been pushing some ridiculous numbers when it comes to measurements lately, and it all shows in the sound quality and signature of their devices, and the DO100 is no different.

This is a fantastic first “high resolution” DAC for all of you audio rookies that just want a no-bull performance at a fair price. I know audio can be confusing, all these numbers, specifications, and the subjectivity of it all, it’s really easy to get lost. So, I’m going to answer your question right now – is the DO100 worth buying if you’re looking for a budget DAC that sounds great? Yes.

I won’t be getting into different frequencies this time, as this device is so neutral that I don’t actually see the point. You’re basically getting a dead-flat sound signature, and if you want any coloration of your audio, you better have headphones that do that. When I pair the DO100 and HO100 combo with my Hifiman Edition XS, the sound is so neutral that it actually amazes me. That quality would have cost you at least 5 times more as recently as 5 years ago. This is the thing that I really like about the audio market nowadays…stuff gets cheaper, and better, at the same time.

So, is a dead-neutral DAC good for you if you’re in the market for your first proper DAC? Well, it depends on a few factors. First, do you really want a neutral tonality? This might be great to get to know the “benchmark” of headphone audio, the way it all “suppose to sound like”. More experienced audiophiles actually tend to go for the sound that is not neutral but to know what kind of sound coloration you like, you have to get your basics done.
The question is – is the DO100 worth getting at $239, when there are things like the JDSLabs Atom DAC+ and Schiit Modi DAC at $119 and $129 respectively? It actually is. First of all, the DO100 is built better than both of them, it has a built-in power supply, balanced outputs, Bluetooth, and remote control. Both Schiit and JDSLabs are brilliant devices (we reviewed both of them), but the DO100 is just a more polished and feature-packed device than both.
When it comes to the actual technical performance, the DO100 doesn’t sound like a $239 DAC. It’s clean, fast, detailed, and well-controlled throughout the entire frequency response. The bass can get very low, the midrange is just neutral and “proper” sounding, and the treble extends all the way to the top octaves, without a hint of sharpness. Take note though, as if you’ll use bright-sounding or overly sharp headphones, the DO100 will not counter it in any way. If you’re very sensitive to the upper frequencies, I’d suggest smooth and rather dark-sounding headphones to pair it with.

There’s one last thing that is worth mentioning. I’ve used the DO100 with different headphones, even the Summit-Fi ones like the Hifiman Susvara, Meze Elite, and Final D8000 Pro. I never had a feeling that this little DAC is holding anything back. Of course, I’ve heard a better sound coming out of these headphones, but at this price, this is very impressive. We’re talking about headphones that cost 20+ times more than the DO100, and they actually sounded great with it.
As for the pairing, the DO100 will pair with everything just great. It will all depend on the type of experience you’re looking for. This is not a DAC that will change the sound signature of your system, quite the opposite actually. It will give you a very neutral signal, and what you’ll do with it next is up to you.

Pairing suggestions​

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Pawel cut the crap and give us some ideas of what to pair the DO100 with! Okay, okay…fine.

1. SMSL DO100 + SMSL HO100 + Hifiman Edition XS

This is the ultimate neutral and flat-sounding system you can get at sub $1000. Every piece of equipment in this setup is just neutral and technically impressive. This setup will give you an uncolored sound that is filled with detail and resolution. I’ve said it once, and I will say it again – You’d have to pay thousands for this kind of performance a couple of years ago, and now it can be yours for under thousand bucks. What a time to be an audiophile.
2. SMSL DO100 + SMSL HO100 + Drop + Hifiman R7DX

Similar to the previous system, but now with a closed-back pair of headphones and even more affordable, actually quite a lot more.
The R7DX (review here) is a closed-back version of the legendary Sennheiser HD600/6xx in some aspects, and if you really need closed-back headphones…this is the setup to get. Neutral, comfortable, functional, and it does everything right. Movies, music, gaming, you’re pretty much set with everything.

3. SMSL DO100 + xDuoo TA-26 + Sennheiser HD6XX

Now we’re getting into something quite different. Here we have that dead-neutral DO100, but it’s paired with a proper all-tube amplifier and a high-impedance classic, the HD6xx by Drop. This setup will be much smoother and warmer sounding than the two previously mentioned, giving you a more colored and “prettier” sound performance. If you want to taste something else, this might be a great way to start. The DO100 makes sure the rest of the system gets a proper quality to work with, the TA-26 will give it that tube goodness, and the 6xx…yeah, this is just class.

4. SMSL DO100 + XI Audio Broadway S + Hifiman HE1000se

Yes, you read it correctly. No, I haven’t gone mad. This setup actually sounds incredible. The DO100 has all the technical capabilities needed for both the Broadway S and the 1000se to shine. Yes, you can get an even better sound with a better DAC. But if you don’t believe in DACs or just simply want this one, this is an absolutely great system that sounds marvelous.

5. SMSL DO100 + SMSL HO100 + Any pair of well-tuned IEM

The star of the show. While listening to the DO100 I was pretty impressed, but when I tried this combo with my Fir Audio Xenon 6 CIEM ($3899) I was absolutely blown away. SMSL points out this “super clean” aspect of these devices, and they’re not lying. This combo has virtually no hiss, pitch-black background, and exceptional clarity. If I listened to this setup and you would tell me that I’m listening to the XENON6 out of a high-end DAP, I would have probably believed it.

Summary​

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The SMSL DO100 is a highly capable DAC coming at a very fair price. It’s well-built with its CNC machined aluminum shell, has neat functions like Bluetooth, a remote control, and balanced output, and most importantly…it’s hyper-clean and neutral sounding. If you’re looking for a DAC that does it all in the $250 market, the DO100 is definitely a wonderful choice.

Highly Recommended.


Gear used during this review for the sake of comparison and as an accompanying equipment:
  • Headphones – Hifiman Susvara, Final D8000 Pro, Audeze LCD-X 2021, Hifiman HE1000se, Abyss Diana PHI, Drop + Sennheiser HD8XX, Crosszone CZ-1, HEDDphone, Meze Empyrean, Drop + Hifiman R7DX, Sennheiser HD6xx, Hifiman Edition XS, Fir Audio XE6, Final A8000,
  • Sources– Topping D90se + A90, Ferrum OOR, EarMen Tradutto, JDSLabs Atom DAC+/AMP+, Cayin N3Pro, xDuoo TA-26, XI Audio Broadway S, SMSL HO100
Big thanks to Aoshida-Audio for providing the DO100 for this review. I wasn’t paid or asked to say anything good or bad about this product, all of the above is just my personal, unbiased opinion. Aoshida-Audio hasn’t seen this review before publishing it.
You can get your SMSL DO100 on Aoshida-Audio here.
Last edited:
J
Jimmyblues1959
Excellent review! Do you know how the DO 100 compares sonically with the Schiit Audio Modius?
Ichos
Ichos
BTW, it doesn't support MQA as you mention in the positives and it does have preamplifier function as the line outputs are adjustable m
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