MAJOR UPDATE 7/3/2023.
I can only recommend this DAC to those who can get a version with the original firmware. And have no need for DoP, and use ASIO for DSD via PC or streamer. It seems that S.M.S.L caused major, major problems with their subsequent firmware release, that went out also on newer hardware versions right into the sales channels.
IF you have a version 1.0, then go for it. Otherwise, I cannot recommend.
There are times when as reviewers, we just get darn lucky. Such was the case with myself and the S.M.S.L D300 sitting on my desktop as I type this review. Yes, the next item planned for evaluation at Euphonic Review was an S.M.S.L product, however the original intent was to hear and evaluate the higher end S.M.S.L SU-10. Then this 'little' D300 caught my eye. Actually, it was the chipset that caught my eye. A DAC chip made by a company with which I had no familiarity; a DAC from a company called ROHM. I have seen instances of hi-fi DACs having commercial DACs squeezed into them like a square peg fitting into round hole, but that is not the case here. This is a legit high fidelity DAC chip designed from the ground up for music. I went looking for it in other solutions, and did indeed find it in the loftiest of places. The venerable Japanese audiophile company Luxman is using this very same DAC chip in its latest 'top-of-the-mark' Player/Processor, the D-10X, costing round about 17,000 US Dollars!! If a company with such a stake as Luxman will place its reputation on something that isn't ESS, AKM, Analog Devices, Wolfson/Cirrus, TI, etc, then they must have found something special, I would think!
As much as I might dream of having the Luxman for test, it will be this diminutive little S.M.S.L D300 which introduces us to the flagship DAC of ROHM's 'MUS-IC' chip lineup, the BD34301EKV.
Some cursory research revealed that ROHM Semiconductor is a Japanese electronic component manufacturer that produces a wide range of products, including integrated circuits, diodes, transistors, LEDs, and other electronic components. Founded in 1958, ROHM today is one of the largest electronic component manufacturers in the world, so they have been around the block for quite some time, and seem to know what they are doing, because as implemented in this particular S.M.S.L DAC, the sound is simply stunning. Lucky me, and lucky anyone else who owns an S.M.S.L D300!!
Unfortunately, however, when I first opened the DAC, I was underwhelmed by its build quality. It is made of a quite thin sheet metal with a rough, industrial black finish. Also, the chassis rattles excessively. Even the PCB rattles on its chassis attachment posts. Not a great start with the visual and tactile experience. The remote is nothing special; it reminds me of a stripped down Roku streamer remote. But, it works and is easy to use. You really can't ask for much more of a remote at this price (unless you want an Emotiva aluminum brick that doubles as a weapon in event of home invasion :-; ).
The LCD screen has somewhat poor off angle viewing contrast, but overall is adequate and functional. It will display the source of playback, the playback outputs (XLR or RCA), as well as the type of playback signal and resolution. Set-up options are displayed here as well. The display, remote and front panel controls all function well and are easily accessible. The D300 is also a very easy DAC to setup, with only a few end-user choices.
Judging from a look on the inside, it appears the S.M.S.L D300 uses a switch mode power supply; one that is very well regulated at that, based on the superb measurements.
Other technical points are this unit receives audio via Asynchronous USB up to 768khz PCM and DSD up to 512fs. Other digital inputs are SPDIF, via both Coaxial and TosLink connectors, which accept up to 192khz PCM. (SPDIF will also accept DSD64, however, take note of the firmware issues and requirements discussed later in the review.) The D300 has balanced XLR outputs that max out at 4V RMS, along with RCA single ended connectors that max out at 2V RMS. There is a variable volume mode setting with max voltage output at 4.5v (XLR) and 2.3v (RCA), however, this works ONLY with PCM signals. DSD stays 'bitperfect' at 1-bit, with no DSP all the way to the final digital/analog hybrid FIR filter. Therefore, DSD is available only in fixed output mode.
As you peruse the D300 menu, you will find a mode called 'HPC' (High Performance/Precision Calculation). When High Precision Calculation Mode is enabled, the microcontroller uses a higher precision floating-point unit, which supports double-precision calculations (64-bit) and provides greater accuracy in mathematical operations.
By utilizing this feature, ROHM's microcontrollers can perform calculations with less rounding error and noise. However, enabling High Precision Calculation Mode may come at the expense of processing speed, as the additional precision requires more processing power and longer calculation times. This means greater latency, which could be an issue if using the D300 DAC with another source such as video. HPC mode is not available on DSD or Double DXD rates. I watched several videos via Plex on my PC with the D300 as audio source. I noted no sync issues with or without HPC mode.
Only a couple of disappointments before we move on. First is yet again we have a lack of MQA. This is seemingly more and more the case for DACs or DAC/headamps in this price range, and I am sure hitting price points has something to do with the omission as it doesn't come free and must be licensed. MQA is a divisive subject, and a great many of you probably will be saying 'So What?' at this point. Personally, I find MQA to sound quite exquisite, and accomplishes exactly what it sets out to do as a DSP, which is to eliminate time smear digitally without adding new time smear at analog conversion. In its place, however, the D300 gives one virtually every kind of Bluetooth connectivity imaginable, including high-res LDAC and aptx HD.
The most MAJOR disappointment, however, is with the behavior of the DAC playing back DSD files, depending on your firmware. While I was waiting for my review unit to arrive, I read quite a few anecdotal reports of very loud 'pops' and 'clicks' when switching between PCM and DSD files, and vice-versa. This is a legacy issue that should have been resolved years ago, so I had a look into the the ROHM BD34301EKV DAC datasheet, and indeed it shows a competent muting relay that should be in effect when switching between the major formats.
Once my review D300 arrived, I experienced no noise issues. My playback software chain starts with Roon server on an HP All-in-one-PC, directly connected to the DAC via WireWorld USB cables, with a Topping Galvanic Isolator before USB enters the DAC.
Trying to trigger this phenomenon noted by quite a large group of users, I switched from DSD Native playback via ASIO to DSD over PCM (DoP), and found in this configuration, there was no DSD playback at all. Only a background hiss was present on any DSD file of any rate. After some research I discovered there is a firmware update issue here, and you must decide how best to deal with it in your system.
For me as a PC user that streams all DSD via native ASIO, there is NO issue at all with the original 1.0 firmware. Using only ASIO, all playback regardless of sample rate or format switching is perfect with no noises, scratches, pops. etc. If you have lots of files on PC and use ASIO, you may like myself wonder what all the fuss is about. Everything works to perfection on firmware 1.0 via a PC. The issue will come if you need to use DoP for DSD streaming. It will not work via firmware 1.0. Firmware version 1.1 is required, and while this fixes the DoP stream issues, it adds its own problems when switching between file types. The 'smooth operator' via ASIO on firmware 1.0 is gone. Now switching file types, especially DSD to PCM and vice versa, can cause very, very loud blasts of noise.
For those of you who NEED DoP (perhaps you have a MAC, or wish to use the SPDIF input for DSD) you will need to update to firmware 1.1. In this case though, I am afraid the consensus is you will experience notably loud, perhaps damaging to ears and/or equipment pops or noises. You will need to take extra care to turn down your preamplifier when switching file types until a hypothetical new firmware drops, presumably with a fix.
AGAIN, this is my 7/3/2023 update. The newer firmware seems to cause more problems than fixed. I have heard of 'bricked' devices, worse measurements, loud 'speaker killer' pops. If you can get a unit with Firmware 1.0, and do NOT need DoP, go for it. What you read here applies. Stay away from any firmware upgrades. As of TODAY, you cannot even download the latest update from S.M.S.L's site, so that should say a lot.
That said, in my playback system as tested, with PC ASIO driver and 1.0 firmware, the S.M.S.L D300 is simply an amazing DAC. I don't think I have ever believed in the 'giant killer' piece of kit, that at a reasonable price, is as good or even better than more expensive industry stalwarts. Sure, some cheaper equipment will acquit itself extremely well. That is really the entire purpose of EuphonicReview.com, finding the best of the best under 10,000 US dollar kit that stands toe to toe with the top 1 percent of the industry. But I feel like I struck gold here. I found the lost Ark, and mapped El Dorado. Drank of the Holy Grail and found the Akashic records. I believe I have found one of the great audio myths, the great Unicorn...... The S.M.S.L D300 is the budget esoterica Giant Slayer.
I let the D300 run for about 48 hours uninterrupted on a loop of my favorite albums before I had any real listen to it. My first impression was that this DAC sounded a lot like iFi Audio. It had little in common sound-wise with the last couple DACs that came through the EuphonicReview.com lab, both of which were 100 percent Delta Sigma DACs. One with AKM tech and one with ESS tech.
And as weeks went by, I keep coming back in my mind to similarities in sound shared between iFi DACs with their Burr-Brown DSD1793 Segment DAC, and this particular S.M.S.L with its ROHM BD34301EKV Segment DAC. Both have excellent detail without being 'overdetailed' or strident. They both possessed a 'naturalness' to them rarely heard with Delta Sigma DACs and more often heard with R2R 'PCM native' type DACs. A very lifelike, realistic sound that is completely natural and never harsh. A sound full of fine detail but never bright. It has a midrange that draws the listener into one of those 4 hour listening sessions where the time just disappears.
Unfortunately ROHM provides little information on how their segment DAC divides each digital word, however, my guess or my gut says it must be doing something similar to the Burr-Brown Segment DACs. We already know that one part of the ROHM segment DAC converts the output of a Delta Sigma Modulator into analog. This is directly indicated. We know as well it is a current segment DAC with voltage used as reference. This information that we do have seems to imply a similar architecture to the Burr-Brown (Texas Instruments) Segment DAC.
However, there are certainly differences in the sound of this S.M.S.L DAC and iFi DACs. The most obvious difference is iFi converters have notably higher even-order harmonic distortion, which gives iFi something of a 'tube like' sound in addition to what has already been discussed.
The S.M.S.L D300 has lower harmonic distortion levels, (however, the analog output still leans to even order harmonics) which means the DAC itself offers less 'editorializing' on the sound of the final product. Whether this is good or bad could be as simple as listener preference. It makes one pine for the 'good old days' of the local store where one could bring their CD's and sit and listen for hours on end and compare different kit to the heart's content, or until the store manager ran one out of said store. One didn't need to read a dozen internet opinions when all you needed to really bring was a pair of ears.
Also similar to the iFi DACs, the S.M.S.L D300 is a true native DSD converter. DSD is converted to analog by using the switches of the segment DAC as a Fixed Impulse Response Digital to Analog Converter/Filter. The process starts with sending the 1 bit serial DSD bitstream through a series of shift registers that could, depending on implementation, run from 4 samples in length, to 32 samples or more. Each set of now many parallel 1 bit signals, offset by one clock cycle, triggers bit-switches that are then summed together as analog current. While indeed remaining on silicon, this is in essence digital FIR filtering implemented in the analog domain. ( 'DAC-less' DSD solutions often do something similar; however the filter is built with discrete analog parts.)
WHY DID YOU LIMBO SO LOW?
DSD Filters 1 and 2 have -3db cutoff frequencies that are especially low at a glance, especially at a DSD64 rate. The -3db cutoff frequency for DSD Filter 1 on DSD64 material is an extremely low 13khz!! The filter coefficients do not change, so a speed doubling of the DSD bitstream doubles the frequency cut of the filter. Which means DSD128 using DSD Filter 1 has a cutoff of 26khz. The pattern continues each time the DSD rate doubles, with DSD Filter 1 cutoff at 52khz with DSD256 material, and 104khz with DSD512 material.
The good part here, though, is unlike the previously reviewed Topping E70V that had a relatively steep DSD64 cutoff at 19khz and NO user choice of alternative filters, the filters in the D300 are quite gentle. (See measurements graphs at end of review.)
The Topping E70V has a fairly steep cutoff at 19khz, which really begins to blur the line between DSD and 48khz PCM. While I do consider the S.M.S.L D300 DSD Filter 1 rolloff starting at 13khz to be too low, the DSD filters native to the ROHM chipset do not approach PCM decimation filters. You will be able to find a DSD filter to your liking here, and I think this is very important, since in my experience, as well as the opinion of others with much more knowledge than me, it is the time domain behavior that gives DSD an advantage. When audio engineers plan for the necessary removal of DSD ultrasonic noise, they must keep in mind time domain performance and never forget the fact that DSD is a 'time splicing' format, and much of its resolution depends on the time domain. Far greater than PCM.
DSD Filters 2 and 3 have cutoffs that match the pattern already set in Filter 1. DSD Filter 2 cutoff starts at 26khz with DSD64, and doubles accordingly throughout; all the way to 208khz at DSD512.
Although a DSD64 FIR cutoff of 52khz is quite well enough, part of me wants to say this is a true native DSD DAC that wants to 'fly', and will respond extremely well to external oversampling or remastering from programs like HQPlayer, Roon and JRiver. Other than the oddity of have a 13khz filter for DSD64 material, this is an exceptional true native DSD DAC and competes as one of the very very best in the price range and beyond.
(Note all tests are done with Roon as source on PC, along with iFi ZEN CAN as analog head-amp with Sennheiser HD650 'phones. Topping galvanic isolator is used between PC source and the S.M.S.L DAC. All connections are balanced. All DSD evaluation uses Filter Choice 3 (52khz), while all PCM evaluation uses the Slow Filter.)
I began my listening tests with a Bill Evans recording that seems to have been 'lost' for some while, then when 'rediscovered', played back as a treasure trove of smooth jazz gifts. (You may read into that the word 'bootleg' lol.) I am writing about the Bill Evans "Another Time /The Hilversum Concert" as re-mastered and digitized by Rene' Laflamme via the 2XHD Fusion system, full of Nagra Tube based decks and electronics. The DSD256 digital version, made on the Merging Horus ADC, reviewed here as played back by the S.M.S.L D300 is a remaster by Laflamme direct from the analog tape domain. In this iteration of the trio we get Evans, along with Eddie Gomez on Bass and Jack DeJohnette on drums. This performance came only days after the more well known 'Some Other Time' by the same three in trio, and the performances are as spectacular as ever.
Beginning the with the track 'Alfie', the unmistakable tonal keystrokes of Bill Evans piano begin slightly to the left and in back of the soundstage, with Eddie Gomez coming in tight on the right and in perfect balance with the piano as if the S.M.S.L is painting two instruments as one, in perfect harmony. Jack DeJohnette's drums sound smooth and natural, the analog nature of the original recording perfectly preserved and represented in digital. Gomez comes in again on the bass with a startlingly realistic 'growl' that might cause one to mistake this under $500 S.M.S.L for a much more expensive reference system. (That will not be the only time for this kind of reaction.)
Around 2 1/2 minutes into the track the complexity begins to pickup, but the lightest of brush strokes by DeJohnette are never lost in the mix no matter their gentle nature. This seems like smooth jazz at its perfection, with every stroke, note, improvisation and rhythmic idea seamlessly blended in the track and always done justice by the S.M.S.L. Part of this is the fact that the S.M.S.L is a true native DSD DAC, and a top notch DSD256 track is destined to shine on a DAC that only uses a FIR filter as the Digital to Analog converter.
Next on the demo list was the Yuki Mabuchi Trio's self-titled album, with Mabuchi on Piano, Del Atkins on Bass, and Bobby Breton on drums. This is a Yarlung Records album, and is one that belongs in every audiophile's collection, whether on Vinyl (from analog tape) or DSD256 Stereo via the same Merging Horus used in the remastering of the previous Bill Evans album. Bob Attiyeh and Arian Jansen are responsible for both the Analog Tape master and this DSD256 stereo master recording.
The track that sets it all into motion is "What is this Thing Called Love?" Instantly noticeable is the large soundstage. The stage could be a bit deeper, but it is certainly wide, in a very impressive manner, creating images well outside the head to the left and right of the Sennheiser HD650 headphones. The bass is distant, but unlike lesser DACs is never lost. Its presence is always there. The string plucks are clear and well defined. Dynamics are a show-off characteristic of this recording, especially with the piano. From crystal clear shimmering highs to powerful bass notes and full chords, the piano is a pure delight in the hands of Yuki Mabuchi. Approximately 3.5 minutes in, the piano seamlessly hands off to the bass, and the purity of tone as these two instruments match and blend into and out of one another is stunningly reproduced. It is in these kind of moments when my critical mind shuts down, and knows I am completely, blissfully satisfied and hearing music, not simply critiquing sound. Around 5 minutes in, it is time for the DAC to surprise me yet gain, as the drums come on with such intensity and dynamics. Transients are super sharp, with no overhang, and individual strikes are captured masterfully. Their variances of tone is easily distinguished! Masterful work, S.M.S.L.
I followed all this DSD256 gluttony with a 24/96 recording of "Stepping Out" by Diana Krall. The track I chose for evaluation was "Between the Devil and the Deep Blue Sea". I am afraid what you are about to read will sound like a broken record. Transient response is truly excellent with no sacrifice of gentleness or nuance. Drum kit brushes are very smooth, but not so smooth they lose their realistic shimmer and overtones on cymbals, as has been the case here at EuphonicReview.com with recently reviewed DACs in this same price range.
Imaging is superb. Everything is in its place in an exacting nature, creating a true illusion of being in the recording space. Bass might be a tad stronger by preference, but it is tight, with no overhang or out of place tone. At this point, the slightly shy bass was the only reminder I was listening to a sub 500 USD DAC! Everything else just sounds 'right' and 'hi-fi'. In words you cannot explain it, but when you hear it, you KNOW it.
I admit I am trying hard yet struggling to find any real criticism here, other than that already mentioned of build quality. Sound quality is first rate, and would deserve a place in almost any hi-fi system. A double blind test between the S.M.S.L D300 and any 10,000 USD DAC of your choice may offer up some surprises. Whether these are good or bad surprises depends on who you will talk to!
The name of my multimedia sites are Euphonic Review, and euphonic and S.M.S.L D300 go perfectly together. This is truly in my ear a euphonic sound that I could listen to for many, many hours on end. What a guilty pleasure for such a lowly price.
The S.M.S.L D300 comes very close to its advertised specifications as determined here in our lab at EuphonicReview.com.
The D300 has over 21 bits of resolution with an A weighted SNR of -126.7db.
Total Harmonic distortion is excellent at -123.1db.
SINAD is a robust 114.1db..
Channel Separation at its worst is a strong -113db.
Jitter measured at 24bit/44khz is a vanishing low 4.5 picoseconds.
Linearity is exceptional. At -115db, maximum error is within 2db.
(-100db error is within 0.1db. -110db, error is within 0.5db)
IM Distortion is very good, ranging from -109db to -112db depending on filter. Oddly enough, the lowest distortion is acheived with the 'slow' filter.
And so the trend continues. Measurements show that most modern DACs are very well engineered. Myself nor anyone else really knows where that crossover point into inaudibility is located; all I can say is I believe we passed whatever it is some time ago.
As usual, if you can, use your ears!! They will always tell you the truth. They speak to you. There are DACs reviewed on this site that measure better than this S.M.S.L, however none of them sound anything like the D300. The D300 musical reproduction trumps them all. So keep these things in mind, and perhaps think of measurements as I do... they will not show you a good piece of kit as much as they will reveal a bad one. Everything checks out here with the S.M.S.L D300. It is as good, maybe even the best sounding piece of kit at this price I have ever heard.
OUR RATING: (0-10 scale. 8 or higher numbers represent best of industry. For the final score calculation, each category is given a (undisclosed) weighting and is tallied for final score. Although perfect 'fairness' is unlikely, our system tries to be as unbiased as possible.
sound quality: 9.2
build quality: 7.0
ease of use: 9.3
TOTAL RATING: 92.7
note, you can click the pics below to enlarge in a lightbox. Mobile devices may treat this in unpredictable ways. It seems 'landscape' mode, phone or tablet turned to the side, gives best results.