In this review, we’ll look at the latest SMSL AKM-based DAC, the SMSL RAW-DAC1. The unit costs $499 USD and can be bought from Shenzhen Audio and other retailers.
Disclaimer: Shenzhen Audio is not related to Headfonia. They sent me the SMSL RAW-DAC1 free of charge to be featured on Headfonia.com.
SMSL
SMSL stands for Foshan Shuangmusanlin Technology Co., Ltd. The Chinese audio manufacturer was founded in 2009. Its main claim to fame has been delivering products of great value where stellar measured performance meets a price available to many. Lately, however, SMSL has been probing higher price ranges with several higher-end offerings for the discerning listener wanting more.
SMSL RAW-DAC1
Currently, the SMSL RAW-DAC1 is the brand’s newest AKM-based converter. It launched together with the RAW-HA1 desktop all-in-one and RAW-MDA1 DAC/amp and was later joined by an ESS-based brother, the RAW Pro-DAC1. I know, I know; we all love SMSL product naming schemes! I can only guess that the theme of the RAW product line is that it delivers the sound in its raw state without anything added or any preparation applied.
Well, who doesn’t love a nice carpaccio?
The RAW-DAC 1 employs Asahi-Kasei’s highest-tier modulator-converter duo – the AK4191 and AK4499EX. The former takes an IIS signal and prepares it into multiple 1-bit data streams for the DAC chip (or chips) to convert into analog audio. For DSD, the signal can be routed directly into the DAC chip for even cleaner playback.
In front of the conversion stage, we have the digital front-end, which features two optical Toslink and two SPDIF inputs. I know many folks will love this! Present is the USB input with a USB-C connector, Bluetooth and IIS with an HDMI LVDS connector.
To make sure that every connection has the best shot of sounding excellent, SMSL use their proprietary CK-03 jitter suppression circuit. Sadly, the chips have milled off markings, so I can only guess what is the actual implementation.
Likely, it’s a custom phase-locked loop, which is a decent way to clean up jittery signals. Fancier stuff like FIFO memory buffers and galvanic isolation are out of the question for a DAC at this price range.
To power the DAC, SMSL have opted for a single encased SMPSU, which generates a 12VDC main voltage, which is then stepped down to +/-11VDC for analog needs and into other lower voltages for digital stuff. Again, multiple dedicated voltage taps from a transformer is what I would have liked better, but it’s rare to see in products at this price range.
I was delighted to notice that noisy voltage converters were quite far away from sensitive clocking circuits.
The analog output stage is competent, but ultimately, there is nothing really to write home about. Texas Instruments opamps (likely OPA1612) are doing both the IV conversion and the line drive. As far as IC opamps go, these are some of the better sounding ones, but the implementation is fairly textbook. A nice touch is the MELF resistors in the critical point of the analog stage.
Overall, the analog stage is designed to excel at measured performance due to the hot-ish 2.5/5Vrms output (the AP555 loves it!), but it is quite in line with my expectations for the price point.
In conclusion, the RAW-DAC1 is competently designed with some appropriate compromises for its intended market positioning and audience. I would have liked some more interesting engineering flourishes to distinguish it from similar units from SMSL’s own stable and its peers like Topping.
And another thing – the circuit is almost identical to the SMSL SU9 Ultra save for the extra digital inputs and a slightly improved PCB design.
Features
- Up to 32bit 768kHz PCM and DSD512 signal support
- Bluetooth 5.1 – LDAC/aptX-Adaptive/aptX/aptX HD/AAC/SBC
- Inputs – USB-C, 2x RCA SPDIF, 2x Toslink, HDMI LVDS I2S and Bluetooth
- Outputs – RCA, XLR
- SNR and DNR – 132dB (XLR), 127dB (RCA) (well below audibility)
- THD+N – <0.00006% (almost immeasurable)
- 2.5/5Vrms output voltage
- Digital volume control
- 4 sound modes and 6 LPFs to choose from
- Remote
Design, Build & Haptics
The SMSL RAW-DAC1 mostly plays it safe when it comes to design. The chassis is made mostly out of bent sheet metal with a nice CNC-milled aluminum faceplate. If installed in an equipment rack, the RAW-DAC1 will only show its front panel, which is dominated by the glossy screen module and a nice contoured encoder knob.
To control the RAW-DAC1 from a distance, an IR remote is included and it makes navigating menus much easier than short and long pressing the knob.
When turned on, the screen shows most of what you’d like to see – volume level, selected input, signal type and bitrate, and active outputs. The legibility is fine for desktop use at arm’s length, but good luck seeing anything but the volume setting from the comfort of your couch.
With two UI options, the “Universal” is more informative, but the number of colours and fonts on the screen make my inner graphic designer cringe. SMSL could also bring other options like a spectrum analyzer and UV-meter for me to be hypnotized by.
The IO on the backside is well-spaced; only the chunkiest of connectors will cause trouble. In terms of connections, I’m not too ecstatic about USB-C, as the older USB-B is more robust, and there’s enough space for it. My other pet peeve is RCA for SPDIF. Yes, it works, but it almost never conforms to the 75-ohm transmission line spec.
With two connections available, one could have easily used BNC for extra signal integrity. Do I miss AES/EBU? Not at this price point. The fact that there are two Toslink and SPDIF inputs will be more helpful.
Sound Signature and Technicalities
My test setup: SMSL SH-X, DROP + SMSL HO150X, Feliks Euforia EVO, Sennheiser HD6XX, Moondrop Para, DCA Noire X, ZMF Auteur Classic, Maytak Audio M6, Softears Volume S, Letshuoer Mystic 8.
Let’s start off with some practicalities. The SMSL RAW-DAC1 is completely silent even with high-gain amplifiers and IEMs. The power-up and shut-down sequences are virtually noiseless, so I wouldn’t hesitate to use the DAC as a preamp with active speakers or power amps.
The volume control is extremely well implemented, and I couldn’t detect a hit in dynamics versus the fixed-volume mode. The 2.5Vrms and 5Vrms output levels are a bit high for consumer audio, so be prepared to turn it down some more. A way to switch to standard levels would be appreciated.
For my testing, I used USB and optical inputs to test whether the DAC is input agnostic and how well it stands up to noise from USB. Toslink from a computer motherboard is likely a worst-case scenario for jitter as well. I’m happy to report that there was no noise when using USB, and there was no shift in performance when using optical.
The jitter suppression seems to be working well! Both RCA and XLR outputs have identical performance, with XLR being +6dB louder and capable of driving longer signal lines without a noise penalty.
I tried Bluetooth input briefly as well, and it’s fine for when you have friends over and they want to show off their music from a smartphone. LDAC and Aptx HD are fine for casual listening, but once you switch over to a wired connection, even lossy music files regain some luster.
USB operation was effortless as my machine found UAC2 drivers automatically. For ASIO playback, a dedicated driver download from SMSL must be made.
The review continues on the second page with more on sound. Click here or use the jumps below.
