SMSL DO300EX

General Information

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rev92

Reviewer at Ear Fidelity
SMSL DO300EX
Pros: Fantastic DAC performance
Functionality
Bluetooth with LDAC
Balanced
Headphone Amp included
Clean, detailed and natural sound
Pairs great with IEMs and easier-to-drive headphones
Cool design, good build quality
Cons: Not the most powerful amp

Introduction to the SMSL DO300EX review​

Reviewed SMSL DO300EX on a case

Another SMSL review here at Ear Fidelity. After reviewing the DO300 in March 2023, I was quite surprised to see the new SMSL DO300EX being released and reviewed this quickly.
However, while the name might be misleading, the DO300EX is not really a successor to the DO300 to begin with. Instead of going for an ESS DAC chip again, SMSL went with a new AK4191+AK4499EX chip to achieve the best possible performance.
Also, while the DO300 was just a DAC, the SMSL DO300EX now has a headphone output built-in as well. Another thing worth mentioning is that the design has changed completely, into what I would consider a much more interesting, unique design now.
I’m going to skip the part where I’m introducing you to the company itself since SMSL is just too well-known for anyone in this hobby to not know about them. Let’s get straight into the review, shall we?

Packaging​

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While the reviewed SMSL DO300EX does look different than their previous models, the unboxing experience remained basically the same.
It comes in a standard, white cardboard box that has been a standard for SMSL for years now, so no surprises here. Inside the box also won’t surprise anyone.
What do you get in the packaging then? First of all, a plastic remote control that we’ve all seen by now. On top of that, there’s a USB cable, a power cable, a Bluetooth antenna, and a user manual.
Nothing fancy, but also nothing to brag about. This is a gold standard when it comes to SMSL packaging and you’re basically getting all you need.
The box itself is fine, no complaints here. It gets the job done, which is to deliver the SMSL DO300EX safely wherever in the world you’re located. It’s not a fancy multi-thousand-dollar piece of equipment, so expecting a nice display box would have been ridiculous.
Overall, the unboxing experience and included accessories are good and SMSL did a good job here.

Design and Build Quality​

Potentiometer of reviewed SMSL DO300EX

Now things are getting really interesting. The DO300EX uses an all-new design language for SMSL, and I must admit, it looks fantastic.
At first, the DO300EX might look like a classic SMSL device, but it’s just a first impression from a few meters away. When you get closer, it starts to look like something completely different.
First of all, the screen that is placed on the front has a great asymmetrical embellishment on top of it, which adds depth to the whole design concept. It looks modern, clean, and unique. Next up, the knob is called “Retro Knob Design” by SMSL itself, and it’s definitely a good description. It has great tactile feedback when turning it, and it’s easy to hold and use it overall.
The actual build quality itself is also spotless. Every edge is made well, there are basically no sharp edges anywhere to be found, the device feels dense and it’s made entirely out of metal. SMSL got us used to good build quality over the past few years, and the DO300EX only improves on it even further. I would go as far as saying that this device feels like it’s 2x more expensive. Nice one!

Tech inside the reviewed SMSL DO300EX​

Connectors available in reviewed SMSL DO300EX

Reviewed DO300EX is a new device by SMSL, so you can surely expect some impressive technology to be used here. Let’s see what’s new this time.
First of all, the new flagship DAC chip, the AK4191+AK4499EX. This Chip combo promises the distortion level to be as low as 0.00006% (-124dB), which is absolutely incredible. We’re living in a crazy time when you can get the TOTL new AKM chip in a DAC/Amp costing less than $500. Brilliant stuff, really.
Next up, the SMSL DO300EX uses a brand-new 3rd-gen XMOS XU-316, with 16 core high-end independent control chips. It uses 5 OPA1612A. It lets you decode DSD of up to DSD512, as well as 32bit/768kHz PCM.
Reviewed SMSL DO300EX can also natively decode MQA, but as most of you know already – MQA is dead, so no comment on that.
The reviewed device has a built-in Bluetooth capability with Bluetooth 5.1. It lets you stream your music wirelessly from any phone, and what’s even more important – it supports LDAC and aptX HD.
SMSL also focuses on the new power supply, which is a super low-noise, stabilized power supply here. It’s said to improve power efficiency, while also reducing power consumption.
Lastly, but definitely not the least important is the headphone amplifier section. Take note that the reviewed SMSL DO300EX is mainly a DAC, and the headphone output is more like an “addition”. It offers up to 1W in 32oHms, which is far from enough for hard-to-drive planars these days. However, if you plan to use efficient headphones or some IEMs, this will cover your needs easily.

Sound​

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Now let’s get into what all of you are waiting for – the sound of the DO300EX.
When I plugged it in for the first time, I was expecting a very reference-like tuning with fantastic technical performance, as one would expect from the new flagship AKM chip. And guess what…I was right!
The new SMSL DAC sounds incredibly fast, natural, and detailed. SMSL once again pushes the limit when it comes to “affordable” audio even further, with a DAC that is truly a marvel in its price range.
Luckily, the times when neutral, budget devices sounded thin and lifeless are long gone, as the DO300EX has nothing like that when it comes to its sound performance. The tuning is spot-on with no coloration, which gives you a wonderful device for testing other equipment. Also, thanks to that, the DO300EX is incredibly versatile when it comes to pairing and music you’re planning to listen to.
Bass
First of all, the bass is snappy, fast, agile and energetic. It has a lot of texture, reaches deep, and never loses control (as long as your headphones can keep up). The low frequencies are not overpowered by any means, nor they are thin-sounding. It sits right in the middle, where it should be, to be honest. This type of bass performance lets you experiment with different amps or headphones, if you want a less “neutral” type of sound.
So for example, when pairing the DO300EX with the Feliks Envy, plugged into the HiFiMAN Susvara, I got an incredibly textured, fast-sounding bass that was truly a reference grade. Literally has zero sloppiness, is not boomy, and never bleeds into the midrange whatsoever.
On the other hand, paired with the SMSL HO100 and the HiFiMAN HE-R9 gave me a much more prominent, thick-sounding bass that was less about the texture and detail, and more about the huge impact and energy of the bass frequencies. At the same time, the HE-R9 were properly driven straight out of the reviewed SMSL DO300EX without any issues, and it’s a good example of a headphone efficient enough for this amp section.
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Midrange
The midrange is clean, and I mean VERY CLEAN. It sounds transparent, insanely detailed, and open, just like you would expect from a new flagship chip DAC.
It doesn’t favor male or female vocals, it does it all. The midrange is not thick sounding, nor is it thin. Once again, it’s just perfect when it comes to the tuning, which SMSL has been known for now.
The airy and detailed presentation gets you a very natural, yet insightful type of listen, and if you pair it with similar-sounding headphones, you’ll get a performance you would not expect from a sub $500 DAC.
Luckily though, there’s nothing artificial-sounding about the midrange of the DO300EX. The timbre of the instruments is spot-on every single time, and it has the ability to show you all the little details. Lastly, not only micro dynamics but also macro dynamics are both great in this DAC.
Treble
The treble is once again clean, fast, and snappy. It has a good weight to it, so it doesn’t sound bright or thin, which is something I’m really sensitive about.
Reviewed SMSL DO300EX just gives you a highly crispy, yet refined treble performance that once again – will show you all the little details that are present in the recording.
However, don’t expect it to sound analytical or digital, because it simply doesn’t. This treble performance sounds just right when it comes to its tuning, and absolutely mind-boggling when we’re considering the technical performance.
Once again, it’ll be up to your headphones of choice if you want a “different” type of sound, rather than just straight-out neutral. The Audeze MM-500 sounded like a proper sound-engineering pair of headphones (which they are, to begin with), while the Meze Elite sounded more romantic, smooth, and full. The DO300EX works great with both, as it gives you that natural, yet highly technical type of sound.
Soundstage
Lastly, the soundstage is also quite impressive. It’s open-sounding, has a lot of air and great separation.
It’s not a surprise for me though, as SMSL has mastered the natural soundstage performance years ago already. A new DAC will not be a “revolution” when it comes to the soundstage performance, as there’s nothing left to achieve to be fair.
However, the credit has to be given where it’s due. The soundstage of the DO300EX is simply excellent and once again, it will depend hugely on your headphones of choice. If you want something a bit more intimate and up-close, the Rosson Audio RAD-0 would be a great choice. If you want a HUGE stage that goes miles in each way, the new Erzetich Charybdis might be the best headphone to pair the DO300EX with on the planet right now.

Comparisons​

SMSL DO300
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Here comes the most important comparison. As I already said in the beginning of this review, the name of the DO300EX might be a bit misleading, as I don’t see it as a straight-up successor to the great DO300.
First of all, the DO300EX has a headphone amplifier section, which the DO300 lacks, so basically no comparison here.
When it comes to the DAC comparison, things are interesting. The DO300 is a bit warmer-sounding, a bit more full-bodied and smooth. The DO300EX however has a more neutral and transparent tuning.
But, the differences don’t end here. The DO300EX is even better than the DO300 when it comes to technical capabilities. It’s more detailed, snappier, faster, and more dynamic. No, it’s not a huge difference, especially since the DO300 is a great DAC to begin with.
However, I find the DO300EX to be even more impressive than the older model, and it seems to push the limit of what’s possible at this price range even further. While doing all this, it also has more functionality than the DO300, especially the headphone amp section. All this for a lower price than the original DO300. This all happened within 6 months of launching the original DO300, which is incredibly impressive. SMSL takes no prisoners, and it just can’t stop releasing more and more impressive devices. KUDOS.

SMSL C200
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This comparison is also quite natural since both devices are DACs with built-in headphone amplifiers.
Take note, however, that the C200 is about half the price of the DO300EX, so we shouldn’t really expect the same level of quality. I’m going to compare the two anyway, and boy oh boy…this is brutal.
The C200 got absolutely outplayed here in every single aspect of the sound quality. The DO300EX is faster, more detailed, has better resolution, more air, and the tuning is even more spot-on.
What C200 does well, the DO300EX does even better, and I’m not even kidding at this point. It’s just a more mature sound, which is also significantly better technically.
Sure, the C200 is still a fantastic buy at around $200, there’s no doubt about it. However, if you have more to spend, and the DO300EX is within your budget, then it’s just a much better-sounding DAC. Twice the price, double the class.

Pairing​

The first thing I want to point out in this paragraph is for you to be aware that I tested the DO300EX with TOTL headphones and IEMs. This should easily give you an idea of how good this $500 DAC is. I never felt that it bottlenecked any of those, rather it just offered a fantastic level of performance, especially considering its price.

HiFiMAN Susvara
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This one is going to be very quick – the DO300EX doesn’t drive the Susvara, it’s not even close. It’s power output of 1W into 32oHms is just not enough for the famous HiFiMAN flagship.
It was obvious from the beginning, but I still wanted to test it.

Meze Elite
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Now we’re talking The wonderful Meze Elite doesn’t need a lot of power to be sounding at its best, and the DO300EX actually does a good job powering these. Of course, it’s not the best that the Elite can sound like, but it’s definitely good enough for sub $500.
When I plugged the DO300EX into an external headphone amplifier though, is when I started to salivate. Once again, its raw DAC performance is just incredible and it lets the Elite shine with all of its power.
This DAC is definitely worthy of pairing with high-end cans like the Meze Elite for example. It won’t be a bottleneck in your system, don’t worry about it.

Fir Audio Radon 6
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Now let’s pair the DO300EX with a high-end IEM, because why not?
The Radon 6 is a monster or an IEM with its class-leading Kinetic Bass technology. This pairing sounds absolutely incredible, as the DO300EX gives this IEM all the detail, resolution, and speed it can use.
Also, the power output of the SMSL DAC is plenty enough to run this IEM like a charm, which results in a sound that is nothing short of high-end worthy. Detailed, thick, natural, and wonderfully fun to listen to.
As I said previously, the DO300EX’s headphone amplifier section works great with IEMs and headphones that are on the “easier to run” side.
So, if you have some dynamic headphones or easy-to-run planars, as well as a few IEMs, this device could be the only one you’ll need for years to come.

SMSL DO300EX – Summary​

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I was expecting a good device when I found out that the reviewed SMSL DO300EX was headed my way, but I wasn’t expecting how good it would actually be.
The best-sounding SMSL DAC I’ve ever heard by some margin, a beautiful yet minimal design, a lot of functionality, and all this at a price that I would easily call a bargain. Ladies and Gentlemen, the SMSL DO300EX gets my highest recommendation possible. You probably can’t get any better for $500 in this hobby right now.

Highly Recommended.


Big thanks to Aoshida-Audio for providing the DO300EX 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.

You can order the DO300EX at Aoshida-Audio here.

Comments

TheHulk

Head-Fier
Amazon has these for $398.65! I couldn't stop myself and bought one. It's your fault as this review pushed me over the top!
 

Nikas

New Head-Fier
Amazon has these for $398.65! I couldn't stop myself and bought one. It's your fault as this review pushed me over the top!
If you don't already have Xduoo MT-604 Tube grab one, might even be on sale will help the 300EX by getting rid of the only Con noted in review.
 

TheHulk

Head-Fier
If you don't already have Xduoo MT-604 Tube grab one, might even be on sale will help the 300EX by getting rid of the only Con noted in review.
I'm new to better, more upscale equipment, in this hobby. My starting point was a pair of HD 580's I bought decades ago. After seeing all of the positive reviews of the Verum One Mk II I decided to take the leap. I bought the original Hip-Dac a while back and love it but of course I need more power to drive the Verum One. I was looking at the Geshelli Labs JS2 with the sparco op amps and the AK4499 dac chip to pair with a more powerful amp but the JS2 alone triples in cost with the upgraded dac and op amps to over $700. When I saw the DO300X with same chip configuration and a usable amp section I figured it would be worth a try. It appears the dac works well but of course no one makes a headphone amp for 8 ohm headphones as far as I can tell. The Xduoo MT-604 looks interesting but still seems underpowered from the specs. Also I'm not sure of the best way to connect the Xduoo MT-604 to the DO300X and use it with my Verum One headphones (like I said a lot of this is new to me). Any help here is greatly appreciated. Thanks! Mike
 

Nikas

New Head-Fier
I'm new to better, more upscale equipment, in this hobby. My starting point was a pair of HD 580's I bought decades ago. After seeing all of the positive reviews of the Verum One Mk II I decided to take the leap. I bought the original Hip-Dac a while back and love it but of course I need more power to drive the Verum One. I was looking at the Geshelli Labs JS2 with the sparco op amps and the AK4499 dac chip to pair with a more powerful amp but the JS2 alone triples in cost with the upgraded dac and op amps to over $700. When I saw the DO300X with same chip configuration and a usable amp section I figured it would be worth a try. It appears the dac works well but of course no one makes a headphone amp for 8 ohm headphones as far as I can tell. The Xduoo MT-604 looks interesting but still seems underpowered from the specs. Also I'm not sure of the best way to connect the Xduoo MT-604 to the DO300X and use it with my Verum One headphones (like I said a lot of this is new to me). Any help here is greatly appreciated. Thanks! Mike

I have two options for you both of which I use for my second system, the Xduoo MT-604 will power the DO300X to a really powerful strong sound, be careful set it half way and turn down the DO300X and them both up slowly because your damage your headphones it is a lot of power, also if you get it you can tube role quite cheap which is quite rewarding and fun.

The other option again I own it is the SMSL HO-200 I also use it for the second setup with the DO300X and it is powerful hit the high gain only if you turn it down almost to zero, never go from low/med to High with volume above quarter.
 

Nikas

New Head-Fier
XLR lead to SMSL HO-200 to DO300X
4.4mm/6.35mm Headphone Output for DO300X
4.4mm/6.35mm/4-Pin Balanced XLR for SMSL HO-200
 

Nikas

New Head-Fier
Xduoo MT-604 4.4mm or HansnBy 4-pin XLR Male to 4.4mm image one



4.4mm Male to 3.5mm Female adapter if your headphones are 3.5mm image two

 

TheHulk

Head-Fier
XLR lead to SMSL HO-200 to DO300X
4.4mm/6.35mm Headphone Output for DO300X
4.4mm/6.35mm/4-Pin Balanced XLR for SMSL HO-200
I currently have 4.4mm Pentacon balanced connector on my Verum One. Based on price and info about SMSL amps being a little unexciting (clinical / boring?) I'm leaning towards the Xduoo MT-604. Clearly I'd be using the DO300X dac but I'm not understanding which connections (outputs / inputs) are used between the Xduoo MT-604 and the DO300X and where and how I'm plugging in my headphones and how to use the gains. I know the DO300X can be used as a pre-amp. May sound dumb but like I said this is all new to me. Thanks again for your help! Mike
 

TheHulk

Head-Fier
I have two options for you both of which I use for my second system, the Xduoo MT-604 will power the DO300X to a really powerful strong sound, be careful set it half way and turn down the DO300X and them both up slowly because your damage your headphones it is a lot of power, also if you get it you can tube role quite cheap which is quite rewarding and fun.

The other option again I own it is the SMSL HO-200 I also use it for the second setup with the DO300X and it is powerful hit the high gain only if you turn it down almost to zero, never go from low/med to High with volume above quarter.
I bought the Xduoo MT-604 on Apos on sale for $143.65 Shipped. Now I need a set of XLR cables to connect it to the SMSL DO300EX. I've seen some positive reviews on Worlds Best Cables (that you can buy on Amazon) but there are so many I'm overwhelmed! Which ones and how long? (My thought is the 604 will sit on top of the DO300EX) If you could send me the link I'd greatly appreciate it. I'm getting pretty stoked! Thanks again. Mike
 

Nikas

New Head-Fier
It doesn't really matter buy/spend what makes you feel Good is all the same, but for reference I tend to use Visiosound 2 x Male XLR to 2 x Female XLR Balanced Microphone Twin Lead/Audio Patch Cable 0.5m OR WORLDS BEST CABLES when they are in stock.



Just plug the xlr to both units and your 4.4mm to xduoo out.

Always unplug headphone when turning xduoo off,
 

TheHulk

Head-Fier
I have two options for you both of which I use for my second system, the Xduoo MT-604 will power the DO300X to a really powerful strong sound, be careful set it half way and turn down the DO300X and them both up slowly because your damage your headphones it is a lot of power, also if you get it you can tube role quite cheap which is quite rewarding and fun.

The other option again I own it is the SMSL HO-200 I also use it for the second setup with the DO300X and it is powerful hit the high gain only if you turn it down almost to zero, never go from low/med to High with volume above quarter.
Just got the xDuoo MT-604 and wondering how to use the gains to best sync with the DO300EX. 1st question: Hi or lo output on DO300EX. 2nd question / thought: My thought was to set the gains somewhere neat their final position on the MT-604 so I can use the single volume on the DO300EX to adjust my listening volume. Should I start with both at zero and inch up the DO300EX or set the MT-604 slightly higher first? Also what's your order for start up once the gains are set? My thought is to turn on the MT-604 a little before I want to listen to allow the tubs to warm up, then turn on the DO300EX, then plug in my headphones and reverse this when turning everything off (so no on / off pops with headphones plugged in). Any help here is greatly appreciated. Thanks again. Mike
 

Nikas

New Head-Fier
Hi output on DO300EX
MT-604 I set mine 3/4 most times and always unplug headphones before power off the MT-604
Use the single volume on the DO300EX to adjust the listening volume
DO300EX to zero and MT-604 whatever power suits your speakers
I just start up my dac first and lower volume then MT-604, headphones plug and play as you want but always unplug the headphones when you turn off the MT-604, that amp has a lot of power, not nice to get a power pop.
 

TheHulk

Head-Fier
Hi output on DO300EX
MT-604 I set mine 3/4 most times and always unplug headphones before power off the MT-604
Use the single volume on the DO300EX to adjust the listening volume
DO300EX to zero and MT-604 whatever power suits your speakers
I just start up my dac first and lower volume then MT-604, headphones plug and play as you want but always unplug the headphones when you turn off the MT-604, that amp has a lot of power, not nice to get a power pop.
Got everything set up adding a WiiM pro to stream using optical input on the DO300EX. Also using a USB connection from my MacBook Air. Got creative and made a fun shelf / stand for everything that I wish I could post a picture of here (but I guess that's a no go?). Loving it all a lot!! Thanks for your help!
 

Nikas

New Head-Fier
Got everything set up adding a WiiM pro to stream using optical input on the DO300EX. Also using a USB connection from my MacBook Air. Got creative and made a fun shelf / stand for everything that I wish I could post a picture of here (but I guess that's a no go?). Loving it all a lot!! Thanks for your help!
That MT-604 sounds better when you swap out the china tubes.
 

Longfellow78

100+ Head-Fier
Hi. I want to buy this but am confused. It is listed as a balanced headphone out, but this review states that it is only a balanced connector for convenience, and not actually a balanced amp.

Also on the website the headphone amp is listed as 1Wx2@32 ohms. I am confused by this. Doesn't this mean 1 watt per channel balanced? I.e. Equivalent to 2 watts unbalanced? If it is not actually a balanced amp, what does 1Wx2 mean? Why not just 1W? Thanks! I am using t60rp headphones which I think like more power and ideally 1w per channel balanced would be fine, but I am not convinced by 1w total if it is unbalanced. thank you very much.

Also is there any point buying this to use as a dedicated amp if I already have a k5 pro ess? Thanks
 
Last edited:

TheHulk

Head-Fier
That MT-604 sounds better when you swap out the china tubes.
Which replacement tubes, where do I get them, and how much? I've seen posts with replacement tubes that made no difference or made it worse. Thanks again. Mike
 

Nikas

New Head-Fier
Which replacement tubes, where do I get them, and how much? I've seen posts with replacement tubes that made no difference or made it worse. Thanks again. Mike

DollaTek Matched Pair 7 Pin GE JAN 5654W Vacuum Tubes Upgrade for 6AK5/6J1/6GB/01/EF95/6J1P Vacuum Tubes. Amazon easy to get in USA.​

 
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