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Hi-Fi

S.M.S.L M8: reach up to 32 bit/384 kHz and DSD64/128 with this compact, yet refined, DAC!

By Barry Moore |

Despite being roundly shunned by audiophiles in their physical format as SACDs, DSD files are currently making a strong breakthrough in the realm of digitalised music. With the aid of digital to analogue converters in decoding them, they are becoming more and more numerous. The S.M.S.L M8 can function in simple and dual mode (DSD64 and DSD128), and adds to this its ability to read DXD files (meaning PCM files sampled at 353 and 384 kHz, respectively!)

We have already had the opportunity to present to you complete testings of two S.M.S.L achievements; that is to say, two devices built by the Chinese brand Shenzhen shuangmusanlin electronics Co. These were the X3 streamer and the small, yet surprisingly rewarding M2 , a portable DAC with headphones amplifier, which was awarded our highest award - a Qobuzism.

So, we have decided to continue to explore this brand?s catalogue by providing a thorough testing of the new M8 DAC.

Perfectly in keeping with the times, the S.M.S.L DAC is able to decode PCM files in up to 32 bit/384 kHz and DSD at 2.8/5.6 MHz, on its USB input.

Using an ES9018K2M chip integrating as many as seven digital filters, S.M.S.L allows the user to profit from this by adapting, to a certain extent, the sound quality according to their liking.

It is also possible to change the DAC M8 by replacing its original switching power supply with a linear one, in keeping with the brand?s audiophile spirit, which is duly adapted to the specifications of the design?s supply. Note, too, that the device is compatible with iOS when using a suitable connector (e.g. the Apple USB camera kit), and with most devices running Android.



Presentation

Simple and elegant, the S.M.S.L M8 digital to analogue converter comes in a naturally anodized, machine-produced aluminium coat.


The photo does not allow us to render it in its full glory, but the S.M.S.L is small (around 22 mm in height, to give you some idea) and possesses a blue OLED display. Despite its size, the device can be easily read, although we concede that to do so one needs good eyesight and close proximity!

This display shows the service entry and the sampling frequency when the file type used is PCM, DSD64, or DSD128, with a used filter.

Two small aluminium buttons are found at opposite ends of the case. The left button is used to start up the device (with a short press) and to enable automatic shutdown in the event of a prolonged absence of input signal (with a long press). The right button lets you select the digital input (short press) and change the filter (when held down).

These digital filters are seven in number: there are three for PCM files (Mini, Slow, and Fast) and four for DSD files (at the cut-off frequencies of 45, 50, 60 or 70 kHz, respectively).

Connection

The S.M.S.L M8 has a digital input compatible with PCM signals of up to 32-bit/384 kHz files, and with DSD files of 2.8 MHz/5.6 MHz. Its coaxial and optical S/PDIF inputs accept PCM files of up to 24-bit/192 kHz.


The analogue signals are available at a fixed level for Cinch jacks, while a coaxial connector allows the connection of 9V currents.

Production

All S.M.S.L M8 electronic parts are regrouped on a single circuit board; the end of which is taken up with a small card supporting the display.


Except for the small glue mound concealing what is probably a modification, the implementation is extremely neat, and no component occupies the other side of the circuit.


The 9V voltage from the power supply is used to power two voltages of + 5V, one serving the conversion stages, and the other facilitating the management and display circuits. Both are stabilized by regulators of the 78M05 type, and there is also a BA033 regulator present (3.3V) which is not visible in the photo below.


An integrated switching converter, in a small plastic case stamped with the S.M.S.L logo, generates symmetric voltages of + or - 12V, which will in turn be used to power operational amplifiers that are used in filtering analogue signals after conversion. These voltages are filtered by self-cell capacitors to remove any potentially obstructive residue. The USB interface is provided by an 8U6C5 XMOS processor, with eight cores working simultaneously on 32 bit and PCM/ DSD accepting signals.


This XMOS chip uses two oscillators with low phase noise, one in 22.5792MHz for sampling at 44.1 kHz, 88.2 kHz, 176.4 kHz and 352.8 kHz, and the other at 24.576MHz for sampling at 48 kHz, 96 kHz 192 kHz and 384 kHz.

The analogue-digital conversion is carried out by a circuit ES9018K2M Sabre32, from the U.S manufacturer ESS, and is compatible with 32 bit PCM files of up to 384 kHz and DSD. It uses the manufacturer?s Hyperstream technology in order to re-sample all incoming signals of 32 bit, and the Time Domain Jitter Eliminator architecture, according to the manufacturer, eliminates all jitter. This chip also integrates digital filters.


The analogue filtering converted signals are in differential mode, and are OPA1612 low noise operational amplifiers from the Texas Instruments SoundPlus ? series. These are used together with Vishay Melf resistors and TDK C0G capacitors, both of top quality, and with which no one will surely complain!

The electronics are managed by a 12LE5608 microcontroller from the ST Microelectronics manufacturer (the 3.3V type BA033 controller can also be seen in this image).


Listening

We have explained that manufacturers are now increasingly likely to offer devices compatible with DSD audio files. There are also those that are beginning to offer a tutorial setting in their player software, particularly for those offering the Foobar2000 for reading DSD files, yet these are still rather rare.

We encourage a rectification of this lack, and ask for more widespread tutorials for the Foobar2000, when used alongside the DSD. This is the absence is also the case for the S.M.S.L converter? We urge the manufacturers/importers to make more of an effort with this!

- Make sure that the previously mentioned plugins foo_out_asio and foo_input_sacd are present, and that each is working. If necessary, look to the installation of the Asio proxy.

- To check for this, go to the Library and select Configure and Components.


- If everything works, click on OK, and then go to the Library and select Configure.


- In Tools choose SACD, then Asio Driver Mode: DSD, and then click on Apply followed by OK.


- Return to Library, then click on Configure, select Playback -> Output -> ASIO, then in the window that subsequently opens, click on Add New.


- Choose XMOS USB Audio 2.0 ST 3037, then click on OK.


- Validate quickly by clicking on Apply, then on OK.


- Return to Library, Configure, then select Output followed by the Device ASIO : foo_dsd_asio, then click on Apply followed by OK.


- The files DSD64 and DSD128 can be read (the spectrum analyser should display nothing).


In listening, we can only but stress the very good sound production provided by the S.M.S.L M8 DAC; its good performance allowing us to experience the vivid emotions that free musical expression always brings about. Here, on the Vivaldi album Vespri per l'Assunzione di Maria Vergine, with Rinaldo Alessandrini directing the Concerto Italiano, the recording is carried by a handsome sound reproduction. It is bright, fine, and full ? certainly no exaggeration ? and overall very pleasant.

We chose to conduct our plays with the help of the optional linear power S.M.S.L P1. The return, to us, seemed no more airy with this than with the original power supplied by the M8.

In essence, this addition proved to be nothing exceptional; the M8 works perfectly in its basic configuration. But, since we did have the P1 power available for testing, it seemed stupid not to use it! The set has a very nice look to it, overall, even if it is on the costly side. But then, at Qobuz, we are always well predisposed to enjoy traditional, linear power supplies!

It should also be noted that, amongst the digital filters available for PCM signals, we chose the ?Mini? (standing for minimum stage, probably), and it was more to our liking than the other two (?Slow? suffered from a small lack of ventilation; on ?Fast? we found the treble and voice a little too projected). The reproduction of Chaleur Humaine, taken from the album of the same name by Christine and the Queens, offers fascinating density. It perfectly highlights the different melodic lines that stand well apart; in particular there is a crisp bass that stands distinct, and clear, in the mixing.

Using DSD64/DSD128 works well too, as shown by the sonic reconstruction of an extract from Arnesen?s Magnificat (test file no. 2L). This recording flows with a great fervour, releasing its sonic emotion with great sweetness (amongst the proposed filter frequencies of 47, 50, 60 and 70 kHz, we chose the latter, to ensure production of the best sound balance).

In conclusion, having selected the filters best fitted to our taste, in playing PCM files as DSD files, the S.M.S.L M8 DAC gave us many beautiful musical moments of enjoyment. We are confident that music lovers will be able to find happiness in this DAC, whose construction betrays a serious amount of care. Notably, the device possesses the option of a linear power supply, which can eventually be added by converting it into a real, small, audiophile-friendly DAC.

Specifications
M8 datasheet
S.M.S.L website
Contact (Contact Audiophonics, or the importer)

Further Reading


Our thanks to Audiophonics for the use of the S.M.S.L M8.

***

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