Soekris "dac1541": DAC/Amp - Stream of Consciousness Impressions

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Torq, Jul 27, 2017.

  1. Torq

    Torq MOT: Headphone.com

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    Søren, the designer of the dac1541, and CEO of Soekris Engineering, very kindly sent us (SBAF) a loaner/tour unit of the dac1541 to evaluate, measure and get some feedback on. This will be included in the “Life after Yggdrasil” thread for the usual comparison/evaluation, but ahead of that I wanted to post some thoughts in a “stream of consciousness” style.

    Why the difference here? Timing mostly; through the end of this month the dac1541 is available for €1110 instead of the usual €1290. My full write-up/comparison is not going to be done by that deadline, so this might help those interested come to a decision in time to take advantage of that offer.

    About the “dac1541”:

    This is a discrete R-2R sign/magnitude balanced DAC and headphone amplifier. It offers USB, AES, BNC/RCA Coax and TOSLINK inputs. The electrical inputs are transformer coupled, so already offer some electrical isolation. There are balanced (4-pin XLR) and single ended (1/4” TRS) headphone outputs, and balanced (dual 3-pin XLR) and single ended (RCA) “line” level outputs. It offers four different cross-feed settings and four different filter options. It’s possible to set the power-on output level for the headphone and “line” outputs independently, as well as which mode the unit fires up in.

    [​IMG]

    Since this is both a DAC and a headphone amp this is filed in the “Amp, DAC/amp” section.

    Notes on these “Impressions”:

    They will initially be focused on listening to the unit as a complete solution - i.e. driving headphones directly. More details on the raw-DAC operation will follow, along with formal comparisons and the results of much more vigorous listening sessions, in the “Life after Yggdrasil” write-up.

    Bear in mind that, as this is a “stream of consciousness” approach, impressions may change as listening progresses. Most notably, there are some things that do not become apparent in short listening sessions nor, necessarily in A/B comparisons … for example fatigue and overall musical enjoyment/engagement are best evaluated over protracted listening. And things that can be initially welcome or impressive can turn out to be grating or superficial.

    The unit has been powered up, playing music, for at least 72 hours straight and the details on the sound are based on listening from that point on.

    And, since I’m doing this quickly, I encourage @soekris to chime in to correct any factual misstatements. My desire to get some thoughts posted is limiting my normal “dig into the guts of the thing” time and will have to wait for my full-write-up.

    Digital Volume Control:

    Volume control is in the digital domain, and is in the chain for both headphone and “line” outputs. This actual volume dial appears to be a stepped encoder and rotates continually (no min/max limiter), with tactile “detents”. If you turn it slowly you get changes in 1 dB steps, turning it faster and those steps become bigger.

    If you push things too far, then the “clipping” light will start to flicker and eventually just be “on”. Keep your playback levels such that this light never illuminates. Which is easy … don’t go over 0 dB on the display and you should be fine – at least for “line-level” usage.

    My understanding is that with the level set to 0 dB, there volume control does not change anything about the signal (typical for digital volume control) and is effectively not-present. This is typically how you’ll want to run the unit in “line” out mode.

    Headphone Output:

    The only source for the headphone “amp” is the DAC itself. Unless I’m wrong about the implementation of the line-out and headphone connections, which is entirely possible, this means that there’s not a practical way to evaluate just the performance of the headphone “amp” part of the unit. So, in essence, this means commentary here, which is where we are going to start, is always about the unit as a whole.

    As always, I’ve used my Abyss, LCD-4, Utopia and HD800S for my listening. I threw in the LCD-2 and HD650 for good measure. I’ll try it with IEMs as I have time - mostly to check for “hiss”.

    The dac1541 has no problem at all driving the Utopia or HD800S, LCD-2 and HD650; speed and control are maintained easily up to the highest volume levels I am willing to listen at.

    With the LCD-4, while it drives pretty well, they’re not quite delivering what I routinely experience them as being capable of. The same is true with the Abyss. This isn’t necessarily affecting the quality of the reproduction per-se, though both the LCD-4 and Abyss have a more “visceral” sense to them when driven via the line-out and through my primary headphone amplifiers. The headphone output is generously powered (3.4W @ 50 ohms), so this is a bit of a surprise.

    I have gotten up around 0 dB on the volume control with the LCD-4 with some tracks, however, and at that point the clipping light will occasionally flicker.

    Sound:

    TL;DR;

    I like it.

    It’s more on the reference*/analytical side than the euphonic/musical side in terms of presentation, exhibits very good detail, is tonally neutral, and has excellent separation. This seems to be a sonically competent entry into the discrete R-2R DAC market.

    The combination of DAC/amp seems easily appropriate for its price-point (probably a bit above that level in fact) and for the types of transducers it is most likely to find itself paired with.

    And in more detail:

    The bulk of the comments in this post are based on listening via the balanced (4-pin XLR) headphone output on the unit. Some results from running it via my WA5-LE or Pro iCAN, but that has mostly been to see if what I’m hearing is a function of the DAC itself or has to do with the power available from the headphone output. Obviously, the full write-up will make it clear which is which and will focus on the DAC side of the equation with external amplification, as will follow-on commentary.



    SOotB:

    Coming straight out of the box, hooking it up via USB, and just listening briefly to make sure things were working …. the sound I get here is very clean, clear and highly detailed/resolving. “Pristine” is the word that came to mind when first considering how the unit sounds. I would, with one interesting (to me) caveat, describe the general tonal presentation as neutral and reference-like*.

    What’s that caveat? When listening more casually I’m slightly more aware of the lower and upper registers than I am normally. That would suggest a very slightly U-shaped character. That’s probably a mental artifact rather than an actual effect – but it’s something I’ll have to revisit in the more detailed listening sessions.

    The sense of detail offered initially is very reminiscent of the better ESS/Sabre implementations, albeit without the “exaggerated” or “fake” nature of the Sabre stuff. That’s a good thing.

    I did not listen a great deal at this point … and instead left the unit to “warm-up”.

    After 72 hours (and change):

    Soren has said the unit didn’t need any burn-in … but I still like to let R-2R designs come to thermal equilibrium before getting into formal evaluation – if nothing else but for the sake of consistency.

    The resolution/detail and clarity is still the first thing that strikes me upon beginning to listen again. This doesn’t change between using the USB input (directly) and the AES input (via Aries). Again, for consistency, I switched to using the Aries via AES as the source for the bulk of my listening.

    While I’m told there shouldn’t be a difference between USB and the various S/PDIF interfaces, I get the sense of a slightly “harder” aspect to the music via USB than I do with AES and S/PDIF inputs. That is NOT to say that this unit actually sounds “hard” via USB, just that I felt it was “harder”. I would take this with a grain of salt, as it's early days and I'm by no means certain which way is preferable or if that sense will persist.

    Tonality is natural and realistic.

    Music has a natural sense of pace without any of the apparent “fast” or “slow” effects that are sometimes perceived. Separation and layering are excellent. This is probably the most obviously noticeable trait of the unit beyond the level of detail on offer.

    There is a deftness to the way notes are handled that is quite enjoyable, with light, rapid, plucks on strings or hits on percussion being conveyed in a very agile and, where appropriate, delicate manner. Notes start seemingly instantly and decay is natural and easy to follow to its conclusion.

    The filters are, with a little focus, audibly variant and after a little time you should be able to tell which you’re listening to. I’m finding myself on the default (filter light is orange) filter about half of the time so far (which is some mix between linear and minimum phase), and with the filter light extinguished indicating a “soft minimum phase” filter. That’s not to say these will wind up as my preferences, or the best the unit sounds … much listening to do there.

    The cross-feed function is meaningfully more obvious in its instant effects than the filter settings. Too early to say if I like it, find it reduces fatigue, or if it improves spacial presentation (left to right). You can definitely tell the difference with each of the settings, however and it’s not mucking up the overall sound, which is a good place to begin.

    ..

    LOTS more listening to do, and lots of specifics to get into … most of which will probably have to wait until next week now.

    --

    *Many seem to take the phrase “reference” as some super-high-praise “this is the shit” affirmation. For me it just means that I’m not hearing specific coloration. Yggdrasil has a “reference” presentation for example, where as “Gungnir MB” I find a little warmer and as a result I would not use the “reference” descriptor there. Compare that to, say, a Linn Akurate DSM … which also has a “reference” like tone but, for me, is easily beaten, overall, by the Gungnir MB. Thus, for me, this term speaks to signature, not quality/performance levels.
     
    Last edited: Jul 27, 2017
  2. Torq

    Torq MOT: Headphone.com

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    In response to several requests, I carved out a few minutes to do a few quick tests and a little listening, with IEMs.

    With SE846, which low-impedance, very sensitive, hiss-monsters, I hear nothing but silence. The same is true with my EE Zeus XRA. No discernible background hiss at all. That's true whether just letting the unit sit, connected, but not playing, when playing a file of silence, and when running tracks that have super-quiet/silent passages in them.

    I'm generally quite sensitive to hiss, so that's an encouraging factor.

    With nothing playing, I can hear a distinct click when the volume control passes between -12 dB and -11 dB, or vice versa. This is a completely consistent thing, and it is NOT in evidence with any of the full-size headphones I've tried. Also, when changing volume levels with music playing, I can occasionally hear a click between "steps" at other levels as well.

    While this unit is, as far as I can tell, a quiet as quiet can be ... with the IEMs I am using you have to have the volume turned WAY down to have it be usable. At -80 dB, which is the lowest setting, you can still clearly hear the music playing. You won't need to strain to, say, readily hear and understand lyrics in a song here. I'm not sure this is a good thing ... I'm accustomed to being able to silence playback simply by turning the volume all the way down. Seems odd, if not specifically a problem.

    With the SE846 I'm still at -40 dB for pretty damn loud listening. This is going to prompt some very specific listening tests as that level of attenuation, or more, doesn't always fare well with digital volume controls. I can't say, in the few minutes I was experimenting, that I noticed any particular change in quality (mathematically such controls, done properly, should be transparent) nor other resultant artifacts - but I've not had nearly enough time here to say definitively that such things are not audibly present yet.

    On the upside, you don't have to worry about channel imbalance at low volume ... there's no of that at all.
     
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  3. gepardcv

    gepardcv Almost "Made"

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    Thank you for these impressions. When you left it on, did the indicator displays dim at all, or was it illuminating the entire room? Does it run warm or hot when left on 24x7?
     
  4. Torq

    Torq MOT: Headphone.com

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    I haven't noticed any dimming of the indicators/volume level. It's not using super-bright LEDs though. It's about the same level as those old LED alarm clocks.

    A couple of degrees above ambient. Barely warm to the touch and you'd only notice it if you were paying attention.
     
  5. GoodEnoughGear

    GoodEnoughGear Evil Dr. Shultz‎

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    @soekris, I imagine this could be rectified in firmware pretty easily. But I'm curious about the -80dB threshold - is that where the digital control starts to degrade?
     
  6. JellyHoo

    JellyHoo Rando

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    Hello Torq,
    Thanks for your impressions.
    I listen to female vocal and pop music using Chord Hugo, and I want to upgrade DAC now.
    Is DAC1541 a good choice for vocal music?
    Thanks a lot.
     
  7. GoodEnoughGear

    GoodEnoughGear Evil Dr. Shultz‎

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    Hi @JellyHoo .

    You'll have to wait for Torq's in depth review next week for more details. In the meantime, please read this and introduce yourself here.

    If you want speculation, if Torq is correct about a slight U shaped FR, that may not be ideal for vocals, depending on your headphones and preferred sound signature. You may want to post a more general question in the all-purpose advice thread, taking care to state your sound preferences and gear so that others can recommend options for you.
     
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  8. soekris

    soekris MOT - Soekris Engineering

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    The -80 dB bottom limit is just something I decided on, did check IEM sensitivities, but didn't expect they to be so sensitive, I don't use them.... I might change the bottom limit.

    The dac1541 frequency response is like a ruler until it start to drop off in the high end by the digital filters....
     
  9. Dackzy

    Dackzy Rando

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    So you tested it with HD 800s', but didn't really say anything about the match. I am in the process of finding a pair of HD 800's, so it would be nice to know if so picky headphones actually sound good on the 1541.
    Other than that you really made a good post.
     
  10. sacredgates

    sacredgates Audio-Technica's high priest

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    great you think Torq made -other than that- a good posting :rolleyes:
    Hope you will be able to contribute with some helpful posts as well...
     
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  11. JeremiahS

    JeremiahS Acquaintance

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    I hope you fix this since there is a lot of emphasis on IEM in the Asian market. I have friends in Indonesia and Singapore who have flagship custom IEM and speakers but skip full-sized headphones entirely.

    Regards,
    Jeremiah
     
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  12. Collusion

    Collusion Acquaintance

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    Let's see if I can confirm Torq's findings next week - I just ordered one!
     
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  13. Torq

    Torq MOT: Headphone.com

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    This effect is very slight. And, again, it's more that I am, for some reason, more aware of the bass and treble aspects of the presentation that normal than a specific belief that what I'm hearing is actually "U shaped".

    This is one of those things that makes "reviewing" audio gear difficult. Almost every DAC I've ever listened to has ruler-flat measurements but for whatever reason they rarely seem to sound this way. Gungnir MB always sounds a bit fuller in the lowest registers to me - but I know how it measures.. Hugo always sounds brighter - same thing here. The actual perception is probably driven by other factors. In the case of the dac1541 it might be down to the detail and clarity making me pay more attention to texture in the bass and focusing on the sense of air in the treble, and that's probably more likely then me hearing any actual deviation-from-flat in the unit's FR.

    Often this effect changes over time - which is a really good indicator that "something else" is at work in making me more aware of certain parts of the response curve.
     
    Last edited: Jul 28, 2017
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  14. Torq

    Torq MOT: Headphone.com

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    No, I tested it with HD800S.


    Not yet, no.

    This is a "stream of consciousness" thread and not a headphone-matching thread. The more detailed stuff will come over time and in the full write-up in my DAC thread.

    You'll have to interpret my thoughts on other headphone matchings anyway, since I don't own the HD800, I own the HD800S, and my experience has been, and preferences are such, that stuff that matches one really well doesn't necessarily match the other.
     
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  15. Priidik

    Priidik Friend

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    The diy version (kind of a rabbit hole, I know) sounds relatively 'colder, calmer' than, say, Yggdrasil, more to my preference.
    Which dacs do you have for direct comparo at hand?
     
  16. Torq

    Torq MOT: Headphone.com

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    For the "Life after Yggdrasil" posts the bulk of the comparison will be against Yggdrasil.

    However, I also have Gungnir MB, Spring DAC L3/KTE, Linn Akurate DSM/1, PS Audio DirectStream* and I should have a Hugo 2** by the time I get back from sailing.

    --

    *Not mine ... borrowing a friend's unit to evaluate it with the new Huron firmware - which will wind up with me updating the DirectStream entry in "Life after Yggdrasil" with whatever I find there. Not listened to it yet, so can't comment beyond that right now.
    **Chord and/or their dealers are about as much use with availability estimates as a fart in a colander, so don't hold your breath on this.
     
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  17. sacredgates

    sacredgates Audio-Technica's high priest

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    Looks like you are not gone sailing yet... so one quick extra question (which you maybe partly answered with "the deftness the way notes are handled" and some other clues...)
    How are initial impressions of micro and macrodynamics?
     
  18. Darren G

    Darren G Friend

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    @Torq Thank you for this expedited review. Enjoy the wind, water, sunshine, sailing is the bomb.
     
  19. Dackzy

    Dackzy Rando

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    Yes I know that you said the S model, I also wrote that "So you tested it with HD 800s' " and then I wrote that I wanted some HD 800's.
     
  20. Dackzy

    Dackzy Rando

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    I am not that active on this forum, since I haven't seen a big need for it. I guess I could be more active and post impressions/reviews of things. The main reason for me being active again is because of these new Soekris combos, I think so far that they hit a sweet spot when it comes to pricing. Though this slight U shape is a bit of a let down for me.
     

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