Schiit Loki - DSD-only for 149 USD

[Miska]

Now the issue becomes: how do I run 2 USB setups?

 

Why would you want to? I keep playing all my PCM content as DSD... TEAC UD-501 and Mytek are always in DSD128 mode, never in anything else for true listening.

[Miska]

I see no active filters on their PCB (OpAmps).

Just one big multifunction chip with three crystals (USB/Ethernet/DSD).

 

I was looking at the same. Can't quite recognize what the big chip is, but I guess it is just USB interface. All the analog stuff is probably at the other side of the board... (makes it easier to isolate the two by ground plane while having short data paths using through vias)

[Miska]

My Loki + Magni combo arrived here yesterday. Initial impression is that it sounds surprisingly good for the price!

 

I will have to try out Magni with some more expensive DACs too. Now I already wonder how Mjolnir would sound like.

 

P.S. Works flawlessly on Linux...

[Miska]

Is this a case of what (I think) you referred before as DSD being simpler to implement at the DAC side?

Now, Loki would be technically simpler to design and build, comparing to a PCM counterpart?

 

In this case, Loki is a bit more complex, since it still carries the PCM legacy in data interface and DAC chip while having the more elaborate analog filter for DSD. To me it looks like Loki is DSD version of the Modi. Same USB interface, same DAC chip and same opamp. But it adds analog input, selection switch, one processor to deal with DoP and more complex analog filter.

 

Since the DAC chip has different kind of analog filter optimal for PCM and DSD, making a proper PCM+DSD version of the DAC would mean double analog stages and relays to switch it. The end result would probably end up costing in range $200 - $250? Worse approach would be to keep Modi's analog stage and just adding DSD support to it, some manufacturers would possibly do it that way, resulting in sub-optimal DSD implementation.

 

Now the key question is which one sounds better, Modi or Loki? Does Loki give much better sound for practically same price? I already regret I didn't order Modi just for comparison... Maybe I'll order it later together with Asgard 2 or Mjolnir...

 

Based on my measurements, main areas where Loki seems to lose to more expensive competition is jitter and isolation performance. I measured it connected to my desktop computer, now I'll need to compare how it performs with ARM-based NAA powered from linear PSU...

[Miska]

Neah, some just filter the crap out of PCM and DSD, at 30kHz and they are set...

 

Then it would look like Lavry or Naim DAC...

 

Since Modi has PCM only up to 96 kHz, using 50 kHz filter for both would be OK.

[Miska]

Miska,

Can you elaborate on your Naim DAC reference? It sounds like you're not a fan.

 

They seem to have quite steep analog filter in their 'DAC' product, based on their white paper it is around 36 dB/octave and starts to cut right after 20 kHz, this way they get enough attenuation by the first image frequencies around the PCM1704 DAC chip sampling rate. (their amplifiers also have quite steep low-pass filter right above 20 kHz, but not as much)

 

How their DAC-V1 behaves remains to be seen...

 

I don't have opinion for or against those, they just have their own design characteristics that are a bit different from many others. I've been every now and then considering DAC-V1 + NAP100 for my living room system...

[Miska]

That's why most of people decided to do OS, to push those analog filters a little 'further' away. PCM1704 at least doesn't generate a lot of ultrasonic noise like the newer D-S chips.

 

It will generate a lot around the multiples of the sampling rate. Since Naim runs it at 705.6/768 kHz they obviously wanted to have a reconstruction (anti-imaging) filter where the attenuation is >144 dB at the first alias band. As it should...

 

Any DAC will create digital images (aliases) around every multiple of the sampling rate.

 

You can for example look at PCM1795 with typical analog reconstruction filter:

 

And compare level of the aliases around every 352.8 kHz coming from the ladder side to level and extent of the noise bump coming from the delta-sigma modulator.

 

Of course another difference is that the noise bump sounds like hiss while the aliases sound like garbled distorted music. Thus intermodulation products of the hiss will also sound like hiss, while intermodulation products of the alias will sound like messed up music (due to inverse spectrum etc).

[Miska]

It's easier to filter out the first 352.8kHz than right at the 20.05kHz...

 

I just don't follow how is that related? Naim DAC uses double that rate, but since the analog roll-off is "just" 36 dB/oct it reaches > -144 dB at 683.55 kHz which is where first image of 44.1 kHz source appears (assuming the digital filter has >144 dB attenuation above 22.05 kHz). -3 dB fc being somewhere around 25 kHz.

 

With 352.8 kHz you should of course have 144 dB attenuation by 330.75 kHz for RedBook sources. Again assuming perfect brickwall digital oversampling filter. 52 dB/oct analog filter would give you that if I calculated correctly.

[Miska]

Do you have any longer term comments on the Loki? How do you like the SQ? Did you ever grab any test data you'd want to share like maybe where they filter at (50KHz?), jitter 60/120 Hz leakage, or anything else? I just ordered one and will have it tomorrow so I am very interested. Thanks!

 

Now I made a blog post about it with some measurement results:

Schiit Loki - affordable DSD DAC - Blogs - Computer Audiophile

 

Since I'm located in Europe, mains related components would be 50/100 Hz and multiples. Since Loki is USB-powered and in my testing it was run from computers with SMPS things are more related to SMPS switch frequencies.

[Miska]

If I chose the Loki, however, the process of converting all "music to DSD on the fly" is a mystery to me. I wonder if the sound would be negatively impacted. Any ideas about that?

 

My take at general level has been that no, it is not negatively impacted, since all modern DAC chips are delta-sigma converters and thus do similar conversion internally when you input PCM. At practical level it of course depends on which one has the best algorithms for doing the work.

 

I've seen some notes by folks saying that MPD or HQPlayer could do the conversions but I haven't been able to find setup instructions specifically addressing the need to do PCM-to-DSD for all non-DSD files.

 

For all the tests I used my player (HQPlayer), as far as I know it is the only Linux player at the moment capable of doing the conversion but I could be wrong. When you enable "DoP" from Settings-dialog and when select "SDM" as output format in main window, any source type is played back in DSD format using selected conversion algorithms.

 

Is the Loki a workable choice for a competent Linux user who is new to serious audio via computer and looking for their first DAC for all their music files?

 

Yes, definitely. If you don't like to use PCM-to-DSD conversion (or HQPlayer), one possibility is to use Schiit Modi for PCM. It is based on same USB and DAC chips, but has different analog stage (and doesn't have the extra processor of Loki that handles DoP protocol). Loki has pass-through switch intended for this kind of purpose.

 

Now I feel kind of sorry I didn't order Modi for comparison purposes...

[Miska]

But you didn't say how you think it sounds

 

Since that's entirely subjective I didn't want to write much about it and my expressive vocabulary for how it sounds is limited in English since it's not my native language. I always recommend people to have a listen first anyway.

 

Loki sounds similar to other DACs based on AKM chip. AKM is maybe on of the smoothest sounding in DSD mode, as well as with external PCM upsampling in PCM mode. Sabre tends to sound hard, while TI is somewhere in the middle. Immediately when I first got the Loki+Magni I did quite long listening session and was pleased with the result, it exceeded my expectations. When I can't stop listening I think it's a good sign...

 

Compared to Fostex which has AK4399 chip and is more expensive, it doesn't have the level of detail Fostex has, but the overall sonic character is similar.

[Miska]

Again, the box lights up that it detects the DSD being played and Media Center shows the file playing. But no sound.

 

One possibility is incompatible USB controller in the computer. I know same thing happening with some computer and DAC combinations. If you have another computer to try with, it may be worth checking out this possibility to save some time...

[Miska]

Have you cheched the "DSD bitstream in DoP format" box (under "audio"->"device settings") and set "Bistream" to DSD (under "Settings"->"Bitstream")?

 

I don't know anything about JRMC, but IIRC Loki lights up the DSD light only when it's receiving a valid DoP stream.

 

Edit: I just confirmed, the second LED doesn't light up if you play PCM, only when you play DoP...