REVIEW: MHDT Labs Stockholm DAC
May 13, 2012 at 2:44 PM Thread Starter Post #1 of 28

s1rrah

Headphoneus Supremus
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Pleased to meet you!
 

As a long time user of the MHDT Labs Havana DAC, I was of course immediately interested when I heard mention of MHDT Labs releasing a new DAC based on the same basic architecture as the Havana but this time with true asynchronous USB implementation and a completely different digital receiver capable of accepting higher bit depth/rate files. And so, already knowing that I positively adored the sonic qualities of the Havana, I just *had* to have a listen to the Stockholm.
 
Fortunately for me, Jiun and the gang of designers at MHDT Labs are some of the most accommodating and “scene-supporting” folks I’ve met in the head-fi/hi-fi arena and so they agreed to loan me a review sample of the Stockholm DAC (EMS shipping from Taiwan, three days…it never ceases to amaze me).
 
 

 
 
For the record, the Stockholm still employs the same dual monolithic PCM56P DACs as the Havana, so technically, I think the final rendered analogue stream is still only 16bit which is fine with me as I'm a fan of that particular DAC architecture (but the Stockholm can receive 192kHz/24bit streams whereas the Havana tops out at 96kHz...weird, technical stuff that I myself don't really understand but which I'll try and explain later). I’m no technician, though and so hopefully Jiun or some other might chime in with clarification.
 
Further, I’m also not much of an high resolution file listener, although I do listen primarily via a computer server and so the high bit rate features of the Stockholm might be better addressed by another reviewer). I *do* have a few “records” in high resolution format, however and I did pay particular attention to them when listening with the Stockholm (more on that below).
 
 
If you happen to not like reading…
 

I could save everybody a good deal of reading by just stating outright that as with the Havana DAC, I personally very much adore the sonic qualities of the Stockholm DAC and for all the same reasons that I so love the Havana. And no, as most “scensters” might probably pontificate, this is not Fan Boi Gush™.
 
I am serious about my music listening; I have preferences and I am hair splitting picky when it comes to being finally pleased. I’ve worked through countless headphones, countless DACS and amplifiers to finally arrive at a listening set up that almost completely pleases me.
 
But it’s still true. I will always quibble, especially since others in my household have totally different valve based gear that at times make me question my decisions (cause said gear is also very bad ass) but … once the dust of my own OCD impulses has settled? I’m very happy with my current set up.  Oh! BTW. Here’s what that amounts too (and also the particular rig I reviewed the Stockholm with):
 
 

 
Headphones: Grado GS1000
Headphone Amplifier: Ray Sam Raptor
RCA Ics: Morrow Audio MA3
Power cable (Stockholm): Audio Arts Power 1

Power cable (Raptor): Zu  Birth

 
As a music listener, my preferences are definitely such that I will always appreciate musicality over clinical delivery...realism in detail over hypersonic retrieval...natural tone/timbre over mechanical coloration; and in regards to such qualities, the Stockholm DAC is a champion performer. I've heard quite a few DACs, some that could be called semi-high end (Neko D100 MkII, Electrocompaniet ECD-1, Channel Islands stuff, Musiland stuff, various CD players from Stello, Marantz, etc.) and others that could be called low end and among all those that I've heard? I definitely still prefer the “non over sampling” (NOS) sound.
 
 
Comparison DACs
 

For the sake of this review (brief though it may be), the three primary DACs I use as counterpoint will be the Neko D100 Mk2 and the Electrocompaniet ECD-1, both of which I consider exceptional DACs and both of which, in certain ways I think have some better and worse qualities than the Stockholm; I’ll also be commenting occasionally on where I feel the Stockholm differs from the Havana DAC. BTW...thanks goes out to Head-fi user “Shellylh” for the ECD-1 loaner and thanks to Neko Audio for allowing me a two week audition of the Neko D100 Mk2 DAC; community in the audio scene and mutual trust enough to allow such opportunities are one of my favorite parts of being involved in forums such as Head-fi...so thanks again.
 
 
Regarding the Music?
 

For what it’s worth you can listen to a short 7 minute .FLAC below which is a collage of sorts, each song featured for about 20 seconds, of many of the tracks I spent serious listening time with; wow, never have so many disparate sorts of music sounded so good mixed together! LOL: 
 
 
 
 
I'm not going to talk much about the individual tracks, though. Nor am I going to bother myself with a list of artists and song titles. 
 
If you wanna hear the sorts of music I spent review time with? Just listen to the above linked MP3. There's about ten of them in there. Each one played for about 30 seconds before segueing to the next.
 
Suffice it to say, I've listened to all sorts of music with the Stockholm DAC and have found the machine well suited to all…and in no way better with one type of music more so than another. I'm an avid fan of listening (it's about the music, after all) and I enjoy the full gamut of available musical genres in my daily listening...lots of classical and chamber, lots of alt country, lots of "stoner" and metal, and electronic as well. But I am not going to mire myself in the particular tone of a piano key strike, how acutely I can hear the composer’s breath, where the drums are coming from, etc. (with good gear, all of that should go without saying).
 
Across the board, I dig it all with the Stockholm DAC ... well, not so much Rap, excepting Rage Against... etc., but that's not really Rap ... but I digress. :wink:
 
 
The Stockholm DAC
 

Before getting in to what I'm sure will be a somewhat brief discussion of the Stockholm's sonic performance, here's a general breakdown of it's mechanical specifications should you be interested in such:
 
Digital Receiver Cirrus Logic CS8416
D/A converter Burr Brown PCM56P-J (pair) 
Frequency response: 20 Hz to 18 kHz (¡Ó 2dB)
Output impedance:  32 ohms
Output level:  1.1 Vrms
USB input 16, 24 bits 44.1 kHz or 48 kHz, 88.2kHz, 96kHz no drivers required
USB input supports Linux, Windows XP, SP2, SP3, Windows Vista, Windows 7 and Apple Mac.
USB input can be synchronous or asynchronous depends on firmware installed
 All other inputs (SPDIF) 16, 24 bits 32 kHz up to 192 kHz
Dimensions clear (W x D X H) 276 x 150 x 60 mm
Dimensions w/ socket (W x D X H) 295 x 170 x 60 mm
Weight 2 kg
Tubes: 5670, 2C51, 396A, 6385, 6CC42, 6854, 6N3, 6854, CV2575, CV4013, CV5894, CV8247, CV2381

 
 

 

 
 
 
 
The Cirrus Logic CS8416 Digital Receiver
 

It's already been mentioned that the Stockholm DAC shares much of the architectural design of the earlier released, very successful and near unanimously lauded Havana DAC; they are both NOS (non over sampling) DACS, both utilize no filters or OPAMPS in the signal path and both utilize a pair of Burr Brown Monolithic PCM56P chips for final L/R output. And having listened to both extensively, I can confirm that in regards to sonics, they are obviously very closely related siblings; I can say already, though, that I prefer the Stockholm, overall, to the Havana as I think the folk at MHDT Labs remedied some of the minor “flaws” present in the earlier released Havana  (more on that below). Where the Stockholm fundamentally differs from the Havana, however, is in the use of a new digital receiver, the Cirrus Logic CS8416 chip, which can receive digital signals up to 192kHz/24bit; the Havana, in retrospect, is limited to 96kHz input since it employs a Cirrus Logic CS8414 chip. As mentioned, both DACs employ the 16bit Burr Brown PCM56 DAC chips, though...so 16bit output is the max that either the Stockholm or the Havana before it can, finally, output (some folks prefer this; I haven't made up my mind, personally as of yet...but I do think the Stockholm sounds better "by ear" with high resolution files than does the Havana).
 
 
Asynchronous USB
 

Another key difference between the Stockholm and it's predecessor, the Havana DAC, is that the Stockholm employs a USB circuit which is capable of "Asynchronous" output. Though the Havana does indeed include USB capabilities, it does not have the asynchronous abilities of the Stockholm. The DAC can still be operated in typical, synchronous USB mode if the user so chooses (this is default, in fact) and the two USB modes are selectable via an easy to use software firmware configuration tool.
 
Now granted, going in to this bit of review listening (it's taken me about four months, btw)...I had no idea what the hell "asynchronous" USB was; therefore, due to my initial ignorance, studying up on the various means of inputting/outputting a USB signal figured prominently on my list of things to do before beginning to write. I was also intrigued by this bit of technical detail as historically (being a long time user of the Havana) I had not used the USB functionality of that DAC much (other than listening briefly) as I vastly preferred the RCA/optical inputs on the Havana DAC over it's USB option (in regards to the Havana, I found the USB to be a bit "flat" and "noisy" when compared to the other input options..).
 
Basically, what I've found via a bit of research (and pardon my lack of technical verbiage in this) is that in typical "synchronous" USB operation, the host computer itself is, for the most part, in control of jitter correction and what not...a scenario that can be complicated by any number of varied things/operations simultaneously being "seen to" by the host computer.
 
Conversely, with "asynchronous" USB, the device in question (this time, the Stockholm DAC) carries with it it's own, on board USB jitter control circuit, and so the host computer has no role at all in regards to managing the various communication processes between itself and the USB device and the DAC itself, via it’s own internal architecture, sees to these processes.
 
And, for what it’s worth, I’ve found the Asynchronous USB to sound quite dramatically better/different than the Havana’s Synchronous implementation. Much more refined, detailed, quiet and very close to matching the sonic qualities of the other signal inputs (coaxial, toslink, BNC). Still, I prefer the latter, more traditional inputs…but that said, I find the asynchronous USB of the Stockholm to be a noticeable improvement over the Havana’s synchronous USB function.
 
 
General Sonic Qualities of the Stockholm
 

As mentioned, I find the Stockholm to be quite obviously a close relative of the Havana DAC. They are both delightfully non-fatiguing DACs; they both render music with an ease and naturalness of tone that invites the listener to simply enjoy the music…and by this I mean that they do not present music in a manner that begs analyzing or “studying” … in my estimation, they are both DACs that truly seem designed for music lovers. This isn’t to say that the Stockholm (or Havana) are boring or unexciting listens, quite to the contrary…they are very detailed and dynamic…spatial qualities are excellent, with the emphasis on good dynamics, with excellent but unexaggerated detail and exceptionally good tone/timbre.
 
Personally, I am a huge critic of high frequency delivery in my audio gear; nothing irks me more than strident, fatiguing high frequencies, trailing “electric sizzles” and the like; it drives me mad. For reference/serious listening, my main cans are a pair of Grado GS1000’s and, as with just about all Grado headphones, they can be a bit nit picky when it comes to getting along with DACS and Amps…primarily (and notoriously) in regards to high frequency treatment. I spent a great deal of time trying DACS and amps that would be most suitable for the GS1000’s and by far, the Stockholm DAC is the very best DAC I have listened too with them. The highs are extremely well placed in the mix, not strident in the least, not sharp edged or fatiguing and yet very brilliant, airy and natural. I’ve heard far too many DACs which just bug the ***** out of me because the equipment seems to want to render the highs in such a bright and unnaturally presented way that I keep thinking I’m listening to a video game or a special effect as opposed to my favorite song. This is definitely not the case with the Stockholm DAC; this DAC is a real champion when it comes to high frequency presentation and especially with Grado headphones (I’ve also spent a great deal of time with the RS1’s and find the Havana/Stockholm to be equally well placed with that can too).
 
Across the board, too…the mids and low frequencies are exceptionally well played. My only quibble would be that occasionally the bass can be just a bit too forward, perhaps not quite as controlled and taut as I’ve heard in other DACs (the Neko DAC comes to mind here, with slightly better, more refined bass)…but this is splitting hairs at best and is a comment made only after countless hours of comparing DACs.
 
A short word should also be said about the dynamic/spatial qualities of the Stockholm, call it sound stage or whatever. Here I find the MHDT design team has definitely improved on the earlier Havana DAC in that the Stockholm somewhat dramatically increases the depth and dynamics of the presentation of music. Sounds are more three dimensional, originating from further out front and to the left and right than with the Havana and generally there is a bit more of that “wow” factor that you sometimes here folks refer to when discussing imaging and sound stage. The Havana is not terrible in this regard by any means, besting many other bits of gear that I’ve heard, but the Stockholm has a more immersive and dynamic presentation for sure. Try as I might, I can never really get a sense of depth to the rear when listening through headphones on *any* sort of set up and when I do try to place sounds that might occur behind me, I generally end up thinking everything sort of sounds like it is coming from behind me and so I can’t really comment on this part of the imaging picture; personally, I think it’s simply a limitation of headphones in general. But front and sides and even a good sense of depth are much more expanded than I was used to with the earlier Havana DAC and in fact better to my ear than some other, more expensive DACS such as the Neko D100 Mk2, which was a tad more narrow and compressed to my ear than the Stockholm. As further counterpoint, the Electrocompaniet ECD-1 was better than both the Stockholm and the Neko in regards to sound stage and imaging, presenting music in an almost eerie, three dimensional manner that would sort of spook me at times.
 
But summing up my appreciation of the Stockholm’s sonic signature would best be made by the simple claim: “It sounds like really fine music.” As a producer/writer of music for two decades now, I am acutely aware of what musical instruments sound like in “real life.” A nylon string on a classical guitar has a distinct and recognizable tone/texture to it that absolutely sets it apart from other types of guitar strings. A piano in a small room has a nuance and tone affected greatly by the size and shape of the room as well as the type of wood and lacquer present in the piano. A floor tom (drum) has a vibration that is near trademark when struck with a certain type of mallet…and the same for various sorts of cymbals…high hats, splash and “rides” all have a character that becomes commonly known and near innate to a listener once such a listener has been surrounded by them in action and as a part of daily life/work…and in this regard, I fancy myself just such a listener. And by far, the MHDT Labs tube DACS … both the Havana and even more so the Stockholm are the most realistic delivery systems for recorded music that I’ve heard to date. 
 
All of the above is, of course, subjective and influenced by my own 44 or so years of living and listening but it remains the case. The Stockholm sounds like really fine music.
 
 
Tubes
 

The Stockholm DAC ships with a General Electric JAN 5670W tube and it sounds just fine, really. But should one so desire, one can definitely find tubes which will influence the final sonics quite dramatically and compared to the stock GE tube, will really raise the bar in so far as dynamics, noise and refinement are concerned; in fact, this is one of my favorite aspects of the Stockholm (or any tube based gear for that matter) that one can completely change the presentation simply by switching out a valve. All of the following tubes work in the Stockholm DAC: 5670, 2C51, 396A, 6385, 6CC42, 6854, 6N3, 6854, CV2575, CV4013, CV5894, CV8247, CV2381
 
Mostly because I want to finish this thing and have long since ran dry of adjectives, I’m going to use a handy little post found in the Havana thread, here at Head-fi.org, to quickly describe the differences among tubes that can be used with the Stockholm but first I’ll mention some highlights regarding my two personal favorite tubes.
 
For the record, my favorite two tubes are the Bendix 6385 and the JAN WE396A tubes; I’ve found no reason to use any other tube, to be honest and they both offer just the right contrast and differences to make just about any listening session perfect. They are a little different, though, for sure with the JAN WE396A being just a tad warmer, a tad more lush and “tubey” and the Bendix 6385 being a bit more “airy” clean and with a greater, sharper emphasis on the highs. Both tubes, however are very clean, exceptionally detailed and offer a real significant upgrade over the stock GE tube that ships with the Stockholm.
 
 

 
 
As far as pricing?
 
The JAN WE396A tube can be found at reputable tube dealers such as tubeworld.com for around $60 to $90 dollars depending on year (the “JW” specification is very important, by the way since this designates the tube as one graded for military usage; regular WE396A tubes can be found for quite a bit cheaper but they are no where near as good as the JW branded tubes. FYI…).
 
The Bendix 6385 tube is rare. Certain popular tube dealers will stock them but you’ll pay a premium and often times the particular dealer will only sell them in pairs. Most popular sites like tubeworld.com will quite commonly sell them for $300 to $400 dollars (per single tube!). Personally, I find it a bit ridiculous to spend half as much as the cost of the DAC itself for a tube, but if you’ve got a fat wallet then go for it. Much better would be to search around forums such as headfi.org and other similar forums and browse the for sale areas, leave messages and ask about. If your lucky (and persistent), you’ll land a NOS tube for $100 to $200 dollars at the most. As a caveat, I will say though that no other tube really does what the Bendix 6385 tube does. I don’t think I’m alone in this opinion, either. It’s just brilliant with the Stockholm (and the Havana) and is very much worth the effort in locating.
 
Otherwise, there’s a great post in the headfi Havana thread that loosely outlines the many posts to date in that thread regarding tube sounds. If your interested, you can read that particular post, here (thanks “Mako44” for compiling them!): Tubes with the Stockholm
 
 
In closing
 

The Stockholm DAC, like it’s predecessor (the Havana) is a music lover’s DAC.
 
Music played live, in The Real World™, is clean and beautiful, sometimes a bit fuzzy around the edges and other times strident and boomy; real music made in real spaces and with real recording instruments could be extended and moody, three dimensional or closed in, it sounds like the brass of a trumpet or the soft gut string of a classical guitar. It twangs and resonates at times. Other times it is punctuated, brief and tight. Music, as played by any given player in any given space and upon any given instrument is as myriad and diverse as the sorts of equipment built to reproduce it...and in my opinion, audio listening gear should present any given recording in a manner that is as true to the recording environment as is possible. To this writer's ear? The Stockholm does it.
 
Otherwise, I’d like to thank Jiun and his fellow designers at MHDT Labs in Taiwan. They’ve been beyond gracious in supporting the audiophile scene, both speaker and headphone based, since I’ve been acquainted with their gear (going back about five years or so). It’s not often you’ll find folk who will not only send you a review unit simply to listen to and write a bit about but also, and as they refine their new design, send you a second one even (should they discover some random problem with the earlier design). :wink: LOL … but that’s just what they did.
 
So good on you guys/gals in Taiwan for not only making a really stellar product and offering it at an insanely reasonable price but thanks for gestures such as this particular Stockholm loaner that, in the end, will do nothing but improve the scene for everybody, the listener and the designer alike.
 
This review has been brought to you by insomnia.
 
:wink:
 
May 13, 2012 at 5:37 PM Post #3 of 28
Hi Joel, fantastic review! Well written, honest and not lacking of details and comparisons.
 
As an old Havana user I've been tempted to upgrade to the Stockholm (or to the balanced version) but I ended up with one of the DAC you've used in your review, the D100. 
We should ask Jiun to organize a loaner program...I might find some space for a new DAC :)
 
May 14, 2012 at 7:46 AM Post #4 of 28
This is an epic review and a treat to read. Thanks for all the effort! You make me want this thing, which is what a postitive review should do. Actually. they should hire you. You'd be the alternative surfer dude that's only hired to make other people lust after the products. Kudos mate. 
 
May 14, 2012 at 3:15 PM Post #6 of 28
Quote:
Thanks for the review.  Do I understand correctly that you are reviewing this DAC, but not using the actual DAC chips that come with it?

 
The PCM56P DAC chips come graded with differring "bins" ... there are "J" grade,  "K" grade and so forth. They are still all the same DAC  chips and the sonic differences are noticeable but not extreme. Others feel different, however and claim that the "K" grade (supposedly the highest quality PCM56P) is dramatically different but I only notice a bit more detail (and in fact, a little bit more "etch") but then that opens a  whole other can of worms cause the afficianados of these chips then claim that differing countries of origin will result in a different tone as well.
 
A mess, really.
 
But for what it's worth, the "J" grade PCM56P's that the Stockholm ships with sound really excellent. Perhaps it's the country of origin in my case, but even though the "K" grade chips I used (Malaysian) are "K" grade ... I still think the "J" grade sound a little better. The "K" grades were a little more strident and (possibly) detailed but I found the high frequencies to be a bit more etched than the stock "J" grade PCM56P that the DAC shipped with. So, in the end, I put the stock DAC chips back in.
 
Oh yeah ... the dual PCM56P chips are in socketed connectors, making rolling DAC chips real easy.
 
:)
 
Best and sorry for the confusion. I'll be editing some of that stuff to clarify.
 
.joel
 
May 14, 2012 at 7:13 PM Post #8 of 28
Quote:
 
You will change your mind when you hear the ORIGINAL Korean PCM56P - K. 
Strident? Edgy? no way!
The Malaysian "K" were not made by BB in my opinion. I do not like them at all.

 
That's what you've mentioned. I look forward to hearing a pair. BTW: I went through every vintage CDP in that list that was circulating a bit back and searched all over the net for like three days. I found a couple old units but they had already been bought.
 
May 16, 2012 at 5:20 AM Post #9 of 28
The Havana has two tubes and the stockholm has one - correct?  I'm new to tubes so bare with me here.  What is the main difference in having 1 or 2 tubes?  Sound, clarity, detail?  Please explain so I can make an educated choice - if there is a such thing.
 
May 16, 2012 at 9:35 AM Post #10 of 28
Quote:
The Havana has two tubes and the stockholm has one - correct?  I'm new to tubes so bare with me here.  What is the main difference in having 1 or 2 tubes?  Sound, clarity, detail?  Please explain so I can make an educated choice - if there is a such thing.

 
The Havana has a single tube. The Stockholm has a single tube. In both cases, the tube is merely a tube "buffer" stage, meaning the tube itself is not used for purposes of gain. The signal is simply passed through the tube buffer, thereby inheriting a bit of the tube sonic influence.
 
The Havana comes in a *balanced* version, also, though ... and this version of the Havana does indeed have two tubes. The balanced version is probably not anything you should worry yourself with though, unless you already know/use balanced equipment. With the balanced version (of any bit of equipment) you are using two distinct and discreet left right architectural channels and therefore the balanced Havana requires two tubes. 
 
More likely than not the regular Havana is what you are wanting/interested in. And it only has a single tube ... the Stockholm, to my knowledge does not come in a balanced version (and I doubt MHDT will release one as the demand for balanced gear is not that great, outside of a niche market of sorts). 
 
Best.
 
.joel
 
May 16, 2012 at 1:21 PM Post #11 of 28
Quote:
 
The Havana has a single tube. The Stockholm has a single tube. In both cases, the tube is merely a tube "buffer" stage, meaning the tube itself is not used for purposes of gain. The signal is simply passed through the tube buffer, thereby inheriting a bit of the tube sonic influence.
 
The Havana comes in a *balanced* version, also, though ... and this version of the Havana does indeed have two tubes. The balanced version is probably not anything you should worry yourself with though, unless you already know/use balanced equipment. With the balanced version (of any bit of equipment) you are using two distinct and discreet left right architectural channels and therefore the balanced Havana requires two tubes. 
 
More likely than not the regular Havana is what you are wanting/interested in. And it only has a single tube ... the Stockholm, to my knowledge does not come in a balanced version (and I doubt MHDT will release one as the demand for balanced gear is not that great, outside of a niche market of sorts). 
 
Best.
 
.joel

 Well the WA22 is a fully balanced design I though I may take advantage of that.  Which of these tubes would fit in the Hanana or the Stockholm:  Sylvania VT231 NOS or the Sylvania 7236 NOS 1963?

 
 
May 16, 2012 at 4:21 PM Post #12 of 28
Quote:
 Well the WA22 is a fully balanced design I though I may take advantage of that.  Which of these tubes would fit in the Hanana or the Stockholm:  Sylvania VT231 NOS or the Sylvania 7236 NOS 1963?

 

 
 
If the WA22 is fully balanced then I'd definitely go with the balanced Havana. As far as those tubes? I have no clue. But the stock tubes that ship with the Havana are really pretty decent and great starting point tubes. 
 
 
 
Jun 20, 2012 at 6:01 AM Post #13 of 28
If one uses a Balanced Stockholm or Havana in a Single End mode are both tube sections on?
 
Jun 20, 2012 at 8:51 AM Post #14 of 28
Quote:
If one uses a Balanced Stockholm or Havana in a Single End mode are both tube sections on?

 
I'm really not sure. Interesting question ... you might try posting the same question in the main Havana thread. Lots of knowledgeable folk over there.
 
Cheers.
 
.joel
 
Jun 20, 2012 at 8:53 AM Post #15 of 28
Thanks Joel, will do.
 

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