Schiit Loki DSD DAC

Hardware Review

Schiit Loki DSD DAC
Tuesday, October 7, 2014
USB DAC
Richard Barclay

Released into the wild in September 2013 the Loki is Schiit’s first dedicated DSD-capable USB DAC. As DSD is essentially a sub-niche within the existing niche of high resolution audio. While it remains to be seen whether DSD will achieve - and more importantly maintain - a meaningful toe-hold in the marketplace, the recent trend of select online retailers stocking an increasing selection of DSD content is encouraging. It is understandable why digital audio hardware manufacturers are keen to capitalise on the recent increase in interest in this format. In keeping with their mission, Schiit explicitly diverged from its competitors’ approach of associating DSD with the upper financial echelons of digital audio and produced the world’s most affordable DSD DAC at the time of launch. This approach effectively protects both the firm and its customers against much of the risk of “DSD going the way of the Dodo”, as Schiit founders Mike Moffat  and Jason Stoddard like to put it. After all, no one likes investing lots of money in a short lived technology!
Despite being a satisfied Bifrost Uber owner with a steadily growing library of high resolution PCM content, I was curious about the speculated sonic differences and/or improvements of DSD versus PCM, and the Loki seemed an effective means of exploring them.

Low-key Loki
Contrary to its ‘double-take’ inducing £149 price tag, the Loki does not compromise on build quality. Its fully custom chassis is machined from 18-gauge, powder-coated steel and draws some streamlined aesthetic inspiration from the bigger toys in the Schiit line-up. Its one pound mass is reassuringly hefty for the diminutive footprint, a scale it shares with the Modi PCM DAC, and Magni and Vali headphone amps, which enables neat stacking if you own one or more of them. However, as with Schiit’s larger and more expensive DAC offerings, the Loki needn’t be pigeon-holed as a headphone audio component. It is equally impressive functioning in a main system and there is nothing to stop you from using it in both concurrently. The front panel button toggles between the converter’s DSD circuitry and the analogue pass-through facility (more on this later). A pair of white LEDs show that the unit is powered up and indicate when a DSD input stream is present. I was quite critical of the brightness of the LEDs deployed in the Bifrost and I’m afraid my criticism carries over to the Loki, only this time my grievance is more acute because on the Loki you get two ‘North stars’ for the price of one. Fortunately I still had an adequate supply of LightDims (sunglasses for LEDs) on hand to calm the glare.

Loki low-down
To elaborate on what I noted in my introduction, the Loki is marketed as a ‘companion DAC’, that is it is DSD-only. Its analogue output stage and filtering has been specifically optimised for DSD. This is advantageous according to its designers, because of marked differences in the data structures between DSD and PCM, the requirements for optimal digital-to-analogue conversion and playback of DSD and PCM are not the same. Without getting too technical, the Loki uses the DoP (DSD over PCM) USB packet specification, where actual DSD is sent over USB without conversion to PCM. A 32-bit microchip processor with proprietary coding then unpacks and reassembles the DSD datastream, which is then passed onto the AKM4396 controller for D/A conversion and then finally through the analogue output stage where the DSD-specific filtering is applied. It is thus claimed that a “cleaner output” is obtained from a topology that isn’t compromised by having to accommodate both DSD and PCM. Of course the downside to this “cleaner output” is that you still need a standalone PCM DAC to play your PCM material (unless you have software to convert PCM to DSD, more on this shortly). For completeness I must draw readers’ attention to the fact that the Loki handles DSD64 only. I suspect however that this won’t be an issue for the majority of the demographic interested in the Loki. Many popular DSD titles that previously existed on SACD are currently being reissued in downloadable DSD64 format, so there should be an adequate selection available to keep the average computer audio enthusiast suitably entertained. (It should be noted that more recent budget converters work at up to four times this sample rate. Ed.)

 

 

Being a companion DAC, switching between PCM and DSD sources necessitates additional ‘hands-on’ user input to what is already considered a clumsy computer procedure. The Loki is equipped with a pair of RCA inputs designed to ‘pass through’ the analogue output of your existing PCM DAC (or whatever line-level source you connect to it). With the Loki’s front panel push button in the ‘out’ position you hear the Loki, and with it in the ‘in’ position you hear your other DAC. This is a very useful feature, especially for users short of amplifier inputs, as without it you would need to set aside input space for both your existing DAC and the Loki. However, the additional input requirement from the user to manually depress the switching button may prove a step too far for those already frustrated by the inconvenience of changing the assigned output source on their music player and/or operating system audio settings every time they wish to listen to a DSD track instead of PCM (and vice versa). Schiit may have missed a trick by not incorporating an automatic DSD/analogue input sensor in the Loki, and one can only assume that its omission was due to it being technically unworkable and/or financially unviable at the price point set for the Loki at the time. One quasi solution - assuming you have enough free input capacity - is to simply reserve separate amplifier inputs for each DAC, as this shifts the manual input switching burden from the Loki onto the amplifier which may be more convenient, particularly if it can be done remotely. It is also worth noting that the Loki’s analogue pass-through facility does not negate the need to have both DACs connected to your computer on separate buses, which could be an inconvenience if you are short of USB ports.

Like its sibling the Modi, the Loki is a USB-only DAC and draws all of its power from the USB port it is connected to. The main advantage of this is that it spares users the grief of siting yet another ‘wall-wart’ power supply. The downside however is that the Loki is always on whenever your computer is on, and the only way to switch it off is to pull the USB cable out, which isn’t the most ergonomic of solutions. A potentially less trivial disadvantage of a device that derives all its power from USB is that, if the USB architecture of your computer isn’t up to the standard it should be, you may experience occasional or at worst regular audible interference. I use the Loki with my Mac Mini running Snow Leopard and Audirvana Plus and can report with confidence that I have experienced no issues with interference, but other platforms and operating systems may vary. If you are indeed one of the unlucky few to experience such problems and these are not remedied by the usual ‘best practice’ solutions, then Schiit’s Wyrd USB Decrapifier may be of interest. It has been designed specifically to cure this issue and can be used with any USB DAC.

If hassle-free listening is your ultimate goal then, as I alluded to earlier, a more ergonomic solution to the repetitive switching tedium is to use the Loki as your ‘one-stop-DAC’. Configuring your playback software to convert PCM content to DSD ‘on-the-fly’ eliminates the need for a PCM DAC, and with it the requirement to manually change software output settings as well as the Loki’s input toggle when switching between PCM and DSD sources. I suspect that the reduction in required user input this yields may not be enough of a reason on its own to convince users to abandon native PCM. Sonic performance will also be a determining factor and this will ultimately depend on the quality of users’ systems, including that of their existing PCM DAC and that of the software used to convert PCM to DSD. It will also depend on whether or not they are fond of the ‘sonic flavour’ of DSD, although it is not unreasonable to expect that fans of native DSD would like the results of PCM converted to DSD. If this second argument still isn’t enough to convince users then perhaps the potential cost saving might. Assuming the pairing of your music player and Loki is as sonically pleasing outputting PCM-to-DSD conversions as it is native DSD, then you could de-clutter your desk and pocket a roll of reddies in the process. Without fueling the debates on the merits of converting PCM sources to DSD, I will reveal that I have chosen not to implement this approach. My DSD library is still small in comparison to my PCM archive and I tend to listen to complete albums, therefore I do not find the switching procedure to be too much of an inconvenience at present. Besides, I have a capable PCM DAC that I really like the sound of, so I shall continue to use it!  If this weren’t the case then I may indeed be more inclined to try using the Loki for everything.!

Smooth Schiit
So what does this Schiit actually sound like? In a word, sophisticated. Listening to DSD64 downloads for the first time through the Loki was one of those genuinely gratifying experiences that only come along once in a while. My most immediate observation was that the Loki subtly flaunts a tonal presentation that is reassuringly similar to my Bifrost Uber; one of neutrality coupled with distinguished transparency, clarity and presence across all frequencies. It is sufficiently well-lit and resolving but retains an effortless smoothness at all times and shows no propensities toward fatigue-inducing stridence or etching. This will be welcome news to those already partial to the Schiit sound, and is an impressive feat given what is a substantial price differential between the two units. Despite very little warm-up and break-in time, the refined spatial qualities of both the DSD format and the DAC soon became apparent. Music was presented with an unrestricted sense of space and ambience that provided an uncannily realistic insight into the physical location of the captured performance. Even heavily-layered recordings seldom sounded restricted or congested. Individual instruments retained adequate air around them and were still able to radiate freely into the listening area. Low-level detail and micro-dynamics were recreated with delicate finesse and allowed the listener to make an all but tangible connection to the musicians. These individual attributes combine to form what one may simply term an improved sense of ‘realism’, and this is what many advocates of DSD claim to be lacking in PCM. In light of the comparisons I have undertaken, I would find it difficult to disagree with this notion.

 

 

It is impossible to directly compare DSD to PCM in a fair and robust manner, there are too many unquantifiable and uncontrollable variables. These start as far back as the respective analogue-to-digital converters used to capture the original performance, include any technical and/or creative divergences in the processes and manipulations that occur thereafter, and conclude with differences in end user playback equipment. That said, on my system at least the native DSD material was, more often than not, sonically more pleasing and engaging than its PCM counterpart, which tended to sacrifice a marginal degree of ‘realism’. This finding held true both for: comparisons of DSD-native and PCM-native downloads (which to the best of my knowledge had been created from the same original analogue tape master); and comparisons of DSD-native downloads and the same material which I converted into 24-bit 88.2kHz PCM myself (and which were thus guaranteed to be from the same master).

To keep this in context and to avoid potentially hyperbolic inferences being drawn, I am not claiming clichéd ‘night and day’ contrasts between DSD and PCM. Any differences that have been noted were very subtle and manifested mainly in the spatial dimension. The intention of this review is not to exclusively favour one format over the other. This was not an influence in my original decision to purchase the Loki and has not become one since. Having the capability to enjoy the DSD format alongside PCM is nevertheless very worthwhile in my opinion, and suffice to say I will continue to grow my library of both formats. Whatever your views on DSD are, there is no denying that - with its absurdly high performance-to-price ratio - the Loki offers very low-risk admission into the world of DSD. It is remarkable that such a level of performance is now available to the masses at a price unthinkable only a couple of years ago. These are definitely exciting, affordable and option-rich times for the computer audio enthusiast.

Verdict
Based purely on sonic performance, it is very difficult to find fault in the Loki. It would certainly be a challenge to unearth a better sounding native-DSD DAC for the money, and I suspect this little converter would also hold its own against competitors in higher price brackets. The Loki offers such ridiculously high quality DSD playback that it almost becomes irrational to make a case against buying it. The decision therefore pivots on whether or not one is willing to tolerate the present ergonomic compromises of a companion DAC. If you are merely curious about what DSD has to offer then the Loki is a low-risk gateway into your new land of discovery. This may then lead you to one of two conclusions: That DSD simply does not merit the hype; or that DSD is ‘music to your ears’ and inspires you to climb the DSD ladder. If indeed the latter and more positive outcome prevails, then you might just find the decision to upgrade from the Loki harder than you expect.

Specifications: 

Frequency Response: 20Hz-20kHz +/-0.3db, 2Hz-200kHz -3dB.
THD: <0.005%, 20Hz-20kHz, at 1V RMS.
IMD: <0.007%, CCIR.
SNR: >100db, unweighted, referenced to 1V RMS.
Crosstalk: >-70dB, 20Hz-20kHz.
Output Impedance: 75 ohms.
USB DOP Input Receiver: C-Media CM6631A.
DOP to DSD Decoding: proprietary Schiit code implemented on 32-bit Microchip processor.
D/A Conversion: AKM4396, in native DSD mode.
DSD capability: DSD64.
Analog Topology: based on AD8616 with DSD-specific filtering.
Power Supply: USB bus powered with significant decoupling, post-regulation, and isolation used throughout.
Power Consumption: 100mA, 5V.
Size WxDxH: 125 x 89 x 32mm (5” x 3.5” x 1.25”).
Weight: 450g (1 lb).

Price: 
£149
Manufacturer Details: 

Schiit Audio
T (323) 230-0079
schiit.com

Distributor Details: 

Electromod
T 01494 956558
www.electromod.co.uk