• MHDT Labs Stockholm v2 Review

    February 21, 2016 Luckbad 0

    Welcome guest reviewer @s1rrah! His reviews of the outstanding MHDT Labs R-2R NOS Tube DACs are excellent and thorough. Enjoy this comprehensive review of the venerated MHDT Labs Stockholm 2.

    MHDT Labs Stockholm v2 : A Review

    Before I even get in to this … let me just say that I’ve already done a review of the originally released MHDT Labs Stockholm DAC. I published it here at Head-fi.org about two years ago (05/13/12) and for what it’s worth? Everything I said in that review (which was hugely positive, btw) also applies here and in regards to this new, Stockholm v2 DAC.

    But MHDT Labs has indeed made some very favorable modifications to their initial design and so read on for the details lurking behind that last claim. They are subtle changes in regards to architecture and mechanics but they make a pretty dramatic difference in sound quality.

    Throughout the following bit of tripe, I’ll refer constantly back to the earlier, v1 Stockholm DAC (and also the Havana DAC) as the primary bit of counterpoint to describe the qualities of this newer version DAC. I’ve already said as much as one can say about the already brilliant and excellent v1 Stockholm and so it’s only obvious that I would constantly be pointing back to that earlier effort in my attempts to describe this new version of MHDT Labs NOS/R2R DAC offering.

    Review minutia and personal idiosyncrasies


    The following will not be a typical review in regards to the commonly accepted format of such; I won’t go in to a track by track listing of the music I listened to and (especially) nor will I wax poetic and dissect the specific and minute aspects of how each track was good or bad with the Stockholm v2 DAC; in regards to reviews of audio equipment? I find this habit of listing songs and carefully picking them apart, sort of ridiculous, really and I always skip that part when reading reviews.

    Rather, I’ll discuss how the Stockholm v2 DAC, as a whole, affected me with music in general. And by this I mean how it resounded with me emotionally first … and technically? second; music is, first, an emotional experience for me (secondly, intellectual/technical).

    But I will indeed also speak a bit in a technical/mechanical regard.  Overall, any given music reproduction system really will reproduce music in different ways in regards to things like detail, bass/mid range/high frequency retrieval, sound stage, speed, “musicality,” articulation, etc and I feel it important to discuss such. But regarding this latter bit … it will be in layman’s terms and certainly won’t be with an air of authority as, I’m certainly not one (an authority).

    As with my earlier review comments on the original Stockholm design. I will include a link at the end of this rambling little bit which will afford you the opportunity to listen to most of the music I used as review material. More than anything, this is provided so that any given reader might better frame a musical context from which the following essay might be better understood. It will simply be a 10 to 15 minute musical collage of sorts featuring 30 to 40 seconds of each track I used as reference material. It should be a fun listen for anyone, really. My musical preferences are diverse, comprising pretty much every genre known and so I figure it beneficial to make such tracks available for others to hear, even if it features only a snippet of each of the 30 or so tracks I actually used as review material. Further, though maybe not at the outset, I will eventually add a time delineated list of artists/records featured in this bit of musical montage should you find any of the brief snippets interesting enough to seek out.

    Some Music


    As mentioned in the outset of this essay, I’m not really too keen on track by track descriptions of the music I used as review material. In the review I wrote for the first Stockholm DAC, I simply included a link to a single file which was a literal “collage” of every track I listened too, all in one edited listen.

    And here, I can find no reason to do anything different.

    As mentioned, I don’t think micro analyzing my personal thoughts/gleanings from each and every track of music I listened to as review material will benefit you, the reader. Much to the contrary … I think that habit is sort of gross and unneccesary.

    But I CAN post an edited mix featuring pretty much everything I listened to while Officially(tm) forming opinions of the Stockholm v2’s qualities and let you download it and listen to it and then form your own opinions, be it listening via a Stockholm DAC or your own personal gear. At least you’ll know where I’ve been musically in regards to this bit and where/what my comments arise from.

    There is quite a bit of music represented here, maybe 20 to 30 individual tracks; I only feature each for about 20 seconds or so but it’s certainly enough to get the flavor of things. From Marta Gomez to Bach to Paul Robeson to Black Tusk .. there’s a pretty decent spread here … so download the file (it’s sort of large at 30mb or so, I apologize) … and enjoy.

    I will be adding a note here in the next few days listing each artist and record featured in this montage on the chance you would like to investigate any given track/artist further. FYI…

    -{{  Review Tracks of Joy and Much Happiness!!!  }-

    (BTW .. the last song in that mix is featured almost in it’s entirety … it’s from a Columbian song writer named Marta Gomez … and that track and pretty much everything she has recorded and released … is sublime … look her up  yo!)… 

    The MHDT Labs Stockholm v2


    And so here we have the Stockholm v2; and as a foreword, it really does continue the impressive streak of highly positive impressions that have been left on my ears over the years by the MDHT design team. I should say that the hi-fi listening scene, in general, has quite appreciated most every offering from the MHDT Labs design team (I honestly can’t recall a negative comment) and this new Stockholm v2 design solidly continues that tradition.

    This particular DAC features the silver body, though it’s also available in an all black design:

    I’m not going to go in to great depth regarding the build quality, short of saying it’s outstanding, solid and meticulous. The DAC has a good “heft” to it, which always pleases me when it comes to audio gear. The fit and finish is simple, elegant, functional and very easy on the eyes. As a visual designer by trade, the look of my audio gear makes a huge impact on how much I ultimately enjoy it; and, where the Stax SRM-323S amp seems a tad blocky and obnoxious (though at the same time exuding a formidable confidence), the Stockholm v2 DAC is sexy, demure and just oozing subdued potency in it’s outlines. I totally dig the look of the thing and it looks great at the listening station, too. And just speaking of the listening station? Here it is in all it’s mid-fi glory:

    Some persons reading this little bit might recall that I authored a review of the original Stockholm DAC a good bit back and that I really liked it. And it should be said, as I gushed in that original review, it’s no fan boi sort of smite that keeps bringing me back to the MHDT Labs DACs; it’s more so my fanatical obsession with a headphone listen that sounds first, highly musical and also, unaffected, not exaggerated or emphasized in any way, natural, effortless and at the same time, nicely detailed and articulate. But foremost, I absolutely require a DAC that sounds like music made in natural spaces with no added or emphasizedfrequency embellishments. Nothing bugs me more than “digital sounding,” digital-to-analogue conversion.

    As a child of the 70’s, and therefore turntables, I am highly sensitive to such “digital sounding” equipment which, unfortunately, seems to litter the current day, DAC landscape. As I’ve said in the past, I want music to sound like music and not like a video game.

    I really don’t get all the up sampling, oversampling and what not voodoo/mysticism; music is recorded once and only a certain amount of sonic information is captured at the time of that recording. That data is captured statically, absolutely. And no amount of post-processing, oversampling or otherwise will extract any more sonic data from that original recording than was first, actually captured at the moment of it’s original capture. Therefore, short of introducing what could be called the sonic equivalent of mathematical artifice to that originally recorded content? I really can’t support the whole up sampling/oversampling thing. To me? And this is a pretty gross analogy, it’s like a woman trying to use massive amounts of make up to try to look “more beautiful” than nature made her to be. But that’s a whole other review… LOL.

    (but as I tried to make clear in the beginning of this tryst, I am no technician and am just making it up as I go along. So keep that in mind…)

    Further, I am a producer/writer of music, for going on two decades now and I have played in all sorts of rooms with all sorts of players, from the guys playing the loudest of Marshall half stacks to the most resonant and precise tones of a skilled, unamped violinist; my preferences in regards to a digital-to-analogue conversion machine are HUGELY influenced by this winded history of live music playing and production; I know what real musical instruments and musicians sound like and I’ve heard them in spaces so confined as a 7′ by 7′ vocal isolation room and all the way up to a vast orchestral room. Those sonic memories tend to resonate…

    And, regarding all of the above? The MHDT DACS work for me; I’ve spent considerable time over the years with the Constantine, The Pardisea+, the Havana v1 and also The Stockholm v1 DAC and I’ve truly enjoyed every moment with them all.

    Stockholm v2 Technical Specs

    Digital Receiver CS8416
    D/A converter PCM56P-J
    Frequency response: 20 Hz to 20 kHz (± 2dB)
    Output impedance: 32 ohms
    Output level: 3V
    All inputs support 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

    More info here: http://dhost.info/mhdtlab/?

    Further, and just speaking of technical specs? Here are a couple photos showing the basic differences between the early version Stockholm and this new Stockholm v2 circuit board design:

    Stockholm v1:

    Stockholm v2:

    As seen in the pics above, the overall layout has changed a bit between the first and second version Stockholm DACs; certain capacitors have been re arranged or added, heat sinks are in differing alignments/locations, etc. I’m no circuit designer by any means and so can’t really comment on the differences but I would assume it has to do with some of the more significant changes to the Stockholm v2 such as total exclusion of the onboard DAC chips internal OPAMPs, a higher output level, etc.

    Necessary technicalities out of the way?


    I am a big fan of the NOS DAC design; also, something that the 7337 headphone purists might scoff at is that I really dig Redbook/16 bit music and have no desire to seek out higher bit rate music, excepting the rare novelty listen.

    I’ve dabbled in the high-res scene and if I’m hair splitting and nit picky and slightly delusional maybe, I can convince myself that I hear differences. But for the most part, my 300GB and 20,000 tracks of music that I listen to constantly, is 99.9%16bit/44khz FLACs.

    I say all that because the Stockholm v2 is able to receive up to 192khz/24bit, but is still outputting via the somewhat aged but also very highly regarded 16 bit dual PCM56P DAC chips. So I’m not sure if it’s appropriate to describe the Stockholm v2 as aimed at the “high res scene” … but more accurate might be to say it’s basically a 16bit output DAC which can also very adroitly receive high resolution files. I will say this, though … high res tracks sound better with the Stockholm v2 DAC than they do with the Havana DAC.

    Also, just regarding high res music listening and MHDT Labs DACs? As I understand it, MHDT Labs has another DAC available, the “Pagoda,” which outputs in a purely 24 bit manner.

    BTW, if you care to read about the technical specs of all the MHDT DACs, then here is a link to a spreadsheet hosted on MHDT Labs website which neatly breaks down the various DAC designs that they currently offer: MHDT Labs DAC Families

    v2 = Some new and very positive improvements

    This new Stockholm v2 DAC differs from it’s first version predecessor, predominantly in the fact that some design wizardry has been applied to the dual monolithic, PCM56P DAC circuit that totally bypasses any involvement of that DAC chips internal OPAMP output.

    It’s true that the original Stockholm and even the Havana DAC were marketed as having “no OPAMPS” as they do not include any actual and standalone OPAMP chips in the design, but technically, they still use operational amplification, only via the PCM56P DAC chips built in output/amplification.

    Lots of persons, including myself, had no clue that the PCM56K DAC chips actually had an operational amplification section, but via some careful reading of the very awesome Havana thread, here at Head-fi, I and others became aware of this fact. It should also be said that it’s awesome that MHDT Labs would respond to such technical discussion, which to me shows that MHDT Labs, as a design team, is genuinely concerned with improving their designs over time. And so, in a strictly purist regard, the Havana (both v1 and v2) and also the first version of the Stockholm, all use a sort of operational amplification.

    In this second version of the Stockholm DAC, this has been bypassed completely and the circuit is now fully discreet; MHDT Labs describes it thus: Current Out, Discrete Transistors I/V, No OPAMP, No feedback.”

    Now I’m no technician, as mentioned elsewhere, but this differs significantly from the earlier Stockholm design and also the current Havana v2 design, which both employ the PCM56K internal OPAMP.

    And as a prelude to further discussion below, the difference in sonic retrieval is quite evidently better with this new v2 design.

    Further, the original Stockholm had a rather diminished output level, something on the order of 1.1V and it was noticeably less than my previous Havana DAC, which was rated as 2.6V. This new Stockholm design has an output level of 3.0V, which makes for a good bit more play in an amplifier’s volume knob and also allows it to work better with a wider variety of user configurations (preamps and what not).



    I currently listen through a fairly resolving headphone set up: a Stax SRM-323S amplifier feeding a pair of Stax SR-404 Limited Edition ear speakers; I also listen with a set of Koss ESP-950 headphones, which are also brilliant. I love this combination for it’s formidable detail, sound stage and insanely rich mid range and otherwise full bodied image. These very fine electrostatic headphones are not the last word in what some listeners would call bass “slam” … but they still represent bass very well and accurately and otherwise, are pretty much unmatched in regards to detail, speed and sound stage. They make a great headphone for reference listening and for judging the merits of any DAC.

    The Stockholm v2 DAC really sits well in front of this Stax set up, providing fantastic detail retrieval and as mentioned, super well extended sound stage. And the NOS design of the Stockholm v2, coupled with the tube buffer it also employs, makes it a nearly perfect DAC for the very clean, very detailed and powerful, solid state Stax SRM-323S amplifier and the incredibly resolving SR-404LE ear speakers. Really, it’s a magical combination and even better in a technically accurate regard than was my previous Ray Samuels Raptor/Grado GS1000 dynamic setup (which I replaced with an all Stax/Electrostat rig about six months ago).

    Further, for the sake of this review, I am listening with a Western Electric JW 396A tube, one of my personal favorites with any of the MHDT Labs tube DACs. The stock GE tube sounds pretty good too, but the JW 396A (and also the Bendix 6385) is a definite upgrade in regards to overall sonics (more clean, better detail, bass … less grain, etc.).

    Just regarding tubes? Here’s a pic of the JW WE396A and Bendix 6385 tube:

    Also, and this applies to any of the MHDT Labs DACs that use tubes (Havana, Stockholm, Constantine, Paradisea, etc.) … a little known tube that is honestly right up there with the Bendix 6385 in regards to cleanliness, detail and gorgeous high frequency retrieval is the humble, AEG 5670 tube. Seriously, look it up and get one if you can find it … a seriously good tube and way less expensive than the Bendix:

    Sonics, sonics, sonics…


    The Stockholm v2 DAC is, without a doubt, sonically superior to the early version Stockholm DAC, which I have spent very much time with. From detail retrieval to sound stage and especially to how the v2 DAC handles any and all high resolution tracks? The v2 DAC is a real sonic gain over the first version. The bass is also much better .. but more below …

    With the Stockholm v2, a quite noticeable bit of “veil” has been removed from the overall sonic image; it’s simply a more dynamic and detailed sounding DAC. The trademark NOS ease of presentation is still there, absolutely. The oh-so-smooth, nearly analogue type window into the music that a well designed NOS DAC can provide is still there, but the level of micro detail has been boosted in a noticeable fashion with the Stockholm v2 (over both the Stockholm v1 and also the Havana DAC). Begrudgingly, I find myself required to use a variation of that most cliché’ of comments used by just about any reviewer moved by an increased clarity in some new listen (forgive me, but): the sounds seem to rise up from a much blacker back ground and each instrument, especially in music employing only a few instruments (chamber music, etc.) is much more defined and discreetly imaged.

    Cliche’ but true…

    Further, and this is almost as dramatically noticeable as the increased resolution, is a quite more remarkably three dimensionaland wider sound stage. The Stockholm v2 DAC now much more approximates the enjoyably “spooky” sort of 3D sound stage that other DACs, such as the Electrocompaniet ECD-1 are so good at (I talked a good bit about the Electrocompaneit ECD-1 in the original review I wrote for the v1 Stockholm).

    I personally really enjoy these changes, which isn’t to say I didn’t enjoy the original Stockholm or the Havana DAC just as much but it’s more so to say, I just didn’t know what I was missing until I heard this new Stockholm design; in many ways, ignorance truly can equal bliss and this is not a bad thing at all, especially in the potentially spendy world of high end audio gear where what you don’t know, really can’t hurt you (or your pocket book for that matter).

    Further, a word should be said regarding bass performance of the Stockholm v2 DAC. I don’t think I’m alone in saying that my one historic quibble with both the Havana DAC and also, the earlier version of the Stockholm DAC was that at times, the bass just wasn’t as deep, extended and especially “taught” and “snappy” as I’ve heard with other DACs (the Neko D100 Mk2 comes to mind here as it’s has some of the nicest bass of any DAC I’ve ever heard).

    With the Stockholm v2, the bass is more refined, more tight and clean than the Havana and Stockholm v1 DAC and it extends down low in a much more clean and less “flubby” manner. It’s quite noticeable when A/B listening between the two machines.

    My hunch is that these positive changes mentioned above are in large part due to the decoupling of the PCM56K’s internal OPAMP … and perhaps too, but less so due to significantly increased output voltage of this new v2 Stockholm. As mentioned, though … overall, the Stockholm v2 is a clearer view of the music than is the Stockholm v1 or the Havana DAC. It is a wholly more engaging listen and is more so approximating the detail level of other DACs that I’ve heard, but while all the while never coming across as unnatural or fatiguing or even noticeably something other than the music you are listening too.

    It’s still an utterly non fatiguing listen; it is true to the best aspects of the traditional NOS DAC architecture but it’s a more clarion listen, more detailed and it throws a much more engaging sound stage than does the previous Stockholm design.

    In Closing


    To sum things up, I think I’ll just steal the closing statement from my earlier review of the Stockholm v1 DAC.  Even though I’ve described marked and definite differences between this newer v2 Stockholm and it’s predecessor … the underlying qualities of musicality, naturalness and non-fatiguing, gorgeous sonics still pertains.

    The folk at MHDT Labs really do know how to milk the classic DAC designs for every ounce off musical goodness:

    “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.”

    Cheers! And happy listening!!!


    – s1rrah

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