R2R Ladder DAC with USB power/input and built-in headphone amp

Soekris dac1101

Average User Rating:
5/5,
  • From the manufacturers' homepage: http://soekris.dk/

    dac1101
    USB Powered DAC / Headamp Discrete R-2R Sign Magnitude DAC

    A small lightweight USB powered DAC, to deliver audio quality never experienced before on the road with a set of high end headphones.

    Or connect it to a matching high end music system at home, to deliver all the favorites from a music server or computer in highest audio quality possible.

    Always with the fantastic natural sound of a discrete R-2R sign magnitude DAC, built with over two hundred tiny ultra precision resistors, driving a high performance zero feedback fully discrete output amplifier capable of driving both low and high impedance headphones as well as line level outputs.

    The music is delivered over an USB interface in both PCM and DSD formats, with precision and ultra low jitter clocking, with digital processing in a programmable FPGA chip with selectable advanced digital filters and digital volume control.

    Technology that used to be reserved to a few DACs costing the same as a car. But now thanks to smart design and automated manufacturing it will be available at a much more reasonable price.

    Specifications:
    THD @ -1db <0.01%
    THD @ -60dB <0.04%
    S/N 20 Khz Bandwith >120 dB unweighted
    Frequency Range +0.1dB -1.0dB 20hz - 20Khz
    USB Input Type B, Isolated, Full/High Speed
    USB Input Mode Selectable Audio Class 1.0 or Audio Class 2.0
    USB Input PCM Up to 24 Bit / 384 Ksps
    USB Input DSD Up to DoP-128 and DSD-256
    Digital volume control -80 dB to +10 dB
    Output Line RCA, 2.0V RMS, Zout 50R
    Output Headphones 6.3mm Phono, 3.5V RMS, Zout 3R

    Headphone Output Power: 400mW into 32 ohms, 120mW into 100 ohms, 40mW into 300 ohms

    Power Consumptation From USB max 3W
    Size 108 x 160 x 20 mm
    Weight 0.3 Kg
    Warranty 3 Years

Recent User Reviews

  1. gr8soundz
    5.0/5,
    "It's (sounds) bigger on the inside."
    Pros - Superb DAC section
    Small size/low price
    Built-in headphone amp
    Driver software optional
    Cons - USB input only
    Lacks a NOS mode
    Note: I have absolutely no affiliation with Soekris and was simply compelled to write this review after experiencing how well their product performs. I wanted to give it 4.5 stars but Head-fi's new design no longer allows for half stars.

    About Me
    Many years ago I started with an Aiwa ‘Super-Bass’ walkman. It was the only one I could afford with both a 3-band equalizer and Dolby (B) noise reduction. I always insisted on original cassettes or dubs made to metal type (CrO2) Maxell or TDK tapes.

    Next up were finally CDs, followed by MiniDiscs and (sadly) MP3s. I spent countless hours ripping CDs to variable bit rates in EAC just to fit more files on DAPs with miniscule storage. Moved on to WAVs but now use mostly FLAC after weeks of re-ripping my entire CD collection.

    Most recent is my current three+ year stint on Head-fi after quietly dabbling in HTPCs.

    My Audio Preferences
    I started out listening to hip-hop, classic R&B, and accapella music but mostly listen to jazz and soul nowadays. I gravitate toward pianos, guitars, horn sections, and dynamic vocals. I prefer detailed, full-bodied, non-fatiguing sound and no longer consider myself a basshead (at least not since my Public Enemy years).


    The Review
    Comparisons among good DACs is the audiophile equivalent of wine tasting, where choices are often made based on personal preferences. Some digital-to-analog converters are certainly more capable but that doesn’t mean others sound bad. Rather, once we find a DAC with a sound signature preferable to our ears, that DAC usually becomes part of a collection (for a while if not permanently).

    For the past few years my main desktop sources were the iDSD Micro and a modified sound card with a Wolfson WM8741 chip. I enjoyed the sound of both but, as usual, wanted more. After reading about R2R DACs I sought one with just the right features for me. I looked at everything from Schiit’s Modi Multibit to R2R units costing over $1000 but settled on the Soekris dac1101 due to it’s features, transportable size, and price.


    What is R2R?
    Soekris is a small Danish company founded in 2001 by Soren Kristensen. They produce a range of internal PC components and recently introduced a line of do-it-yourself (DIY) discrete R2R sign magnitude DAC boards.

    I’ve tried several times (unsuccessfully) to describe differences between R2R and delta-sigma (DS) designs but believe the manufacturer says it better here: http://www.soekris.dk/products.html

    “.....good R-2R chips are expensive to manufacturer, and soon the Delta Sigma DAC technology started to catch on, not because they are better, but because they can be manufactured using low cost high volume chip processing, avoiding the needed costly trimming process needed for multibit DAC chips....”

    “A Delta Sigma DAC take the 16-24 samples and converter them to 1 bit samples, later 2-5 bit samples, at higher speed. That creates high levels of noise, but by using a process called Noise Shaping that noise is moved up in frequency above that you can hear. Unfortunate that process creates a number of side effects which the Delta Sigma chip manufactures all try to reduce.... Now we are seeing the R-2R DAC return as the sound is just much more naturally.”


    The dac1101
    The dac1101 is a USB powered dac/amp combo based around Soekris' discrete R2R sign magnitude design. It’s also among few ladder DACs available and one of even fewer with native DSD capability (up to 256).

    Rather than purchase one of their boards and attempt to build my own DAC around it, I ordered the dac1101 instead. The reduced price of $390 (originally $650) for a finished product was just over $100 more than their best specced DIY board. However, there’s so much functionality packed into this small unit that I feel the original price was more than worth it and the sale price is a downright steal.

    Soekris has since closed their U.S. distributor but the dac1101 is still available on their www.soekris.eu site. They’ve also announced additional new DACs (with varying levels of i/o ports and progressively higher spec resistors) as part of their audiophile line for release this summer.

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    My order arrived double packed in an unassuming white box containing the dac1101, USB A to B cable, 3.5mm to 6.3mm adapter, and printed instruction manual.

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    Construction is all aluminum apart from the plastic filter button. The DAC has a brushed, gun-metal finish capped by black anodized front and rear plates. There are eight LEDs out front highlighting everything from sample-rates to volume and filter settings. To the right is a 6.3mm headphone output for use as a dac/amp. The front is labeled with a basic but legible white font indicating the DAC's DIY roots.

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    The metal volume knob is fully digital yet has a very precise feel and the red “VOL” light changes intensity depending on the output level. There is no gain setting but (quoted from Soren on diyforum.com): “The dac1101 actually changes the gain in the output amplifier as needed, but it's integrated with the digital volume control so you don't notice it.” Output is fully discrete with no negative feedback and high bias, class A/B power.

    Volume ranges from -80dB to 10dB (with each silent tick of the knob being 1dB) so it’s easy to fix output at 0dB by maxing out the volume then turning it counterclockwise ten clicks. I eventually settled on -1dB for the line out to prevent overloading the signal into my headphone amp.

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    Out back are the type B port, USB mode switch, filter push-button, line/phones switch, and RCA line outputs.

    Pressing and holding the filter button for roughly 4 to 5 seconds stores the current volume and filter settings, with one volume setting for the headphone jack and another for the line out. Both outputs share whichever filter is currently stored. So, when using sensitive headphones, there’s no need to reduce the volume each time the Soekris starts up.

    However, there’s a nice detail not mentioned in the manual. Initially, the line out volume was variable but, after saving settings, the knob no longer changed the level. Repeating the process confirmed that every other save switches the line out from variable to fixed, meaning the dac1101 can easily go from DAC to preamp.

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    The bottom is surrounded by a thin layer of rubber which keeps the DAC low and stable during use.

    photo via http://www.soekris.dk/
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    Inside, with dual 25-bit resistor-ladder networks, the dac1101 maintains greater than 16-bits of resolution even in worst case scenarios. The ladders (consisting of over 200 small resistors) take up a lot of real-estate, making the dac1101's size and features quite an achievement.

    Unfortunately, the Soekris isn't non-oversampling (NOS) and upsamples output to 352/384kHz since it's creator believes in oversampling to take full advantage of the hardware's capabilities.


    The Setup
    I wanted my opinion to reflect as much of the DAC’s capabilities rather than the quality of the USB connection. In my case that means a fully fanless PC, low ripple power supply, motherboard with dedicated usb ports for DAC use, plus external cleaners like the AudioQuest Jitterbug and iFi iPurifier2. Extreme measures, but USB may never be the best way to transmit audio signals and space is very limited within the Soekris’ small confines. Doubling as the power source in addition to handling up to native DSD256, USB was the only viable solution for this dac/amp combo.

    Another benefit of USB is being able to use DACs with portable sources. Though not officially supported, I was able to use the dac1101 with my Android phone connected through a powered USB hub. With no drivers needed in USB Mode 1 (though limited to 96kHz), it’s a nice option to have when no computer is available.

    As I write this, the DAC has about 200 hours on it and is powered on 24/7 (with my PC in standby when not in use). Aside from the first few hours of warm-up, I didn't hear any major changes after burn-in. Even after hours of use, the DAC barely gets warm to the touch.


    How Does it Sound?
    At first listen, I could plainly hear extra details in each recording. Faint layers of sound that were previously difficult to discern were now clearly present, going so far as to bounce (reflect) off the inner ear cups of my Sony Z7s.

    Then I let the dac1101 warm-up for a few hours and, suddenly, everything sounded more organic and cohesive. I never imagined lowly mp3s could exhibit such smoothness, sounding more musical than they're supposed to. No matter what I threw at it, the Soekris unleashed enjoyable sound from everything but the worst masters. It’s easily the most resolving DAC I've used, likewise showing no mercy for poorer recordings. Bit-rates aside, badly mastered albums and crappy files sound ‘as-is’ with the Soekris.

    It does sound a bit brighter than I’m used to but is neither sibilant nor fatiguing. Its overall sound is much more natural (dare I say more analog), bringing my setup closer to the live music and instruments I’d heard growing up.

    I have yet to hear any other ladder DACs (the iDSD Micro is a hybrid multibit) so individual comparisons aren’t possible. However, compared to all other DACs I have heard, the dac1101’s:

    Background is very dark with no detectable hiss (from headphones at least; I don’t use iems so uncertain how those would fare).

    Soundstage width is a bit larger while soundstage depth is significantly increased.

    Separation, imaging, and placement are the best yet.

    Bass (along with the overall sound) is cleaner and quantity is sufficient.

    Micro details that were difficult to hear are now front and center.

    Tone is fairly neutral but each of the four filters has a subtle effect on the output: Linear Phase (or brickwall filter; red), Linear/Min mix (orange), Minimum Phase (or butterworth filter; green), or Soft Min Phase (off).

    I also played a few DSD test files and, typical of mega-oversampled DSD, they sounded great. Many DACs (including delta-sigma) handle DSD well but, unlike the dac1101, they have trouble maintaining similar quality with lower bitrate material.

    The headphone out is equally impressive with very little distortion. It’s more powerful than anticipated but can’t quite fill out the lows and mids of the Beyerdynamic T1.2 (which can sound too thin at lower volumes and too bright at higher ones).

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    Direct pairing with the headphone out is great with neutral to warm headphones like the Oppo PM-3 and the Sony MDR-Z7 which (imo) are near perfect matches.

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    When paired with the equally diminutive Schiit Vali hybrid amp, the combo provides a full-bodied, spacious sound with (honestly) a bit more detail (and possibly signal strength) than the amp can handle. You’ll need to use the dac1101’s headphone out (or a higher tier amp) for that extra dose of solid-state speed and detail. However, this setup is perfect for me and I believe it would very difficult to beat their combined performance in either size or price.


    The Conclusion
    The best way to summarize how the the dac1101 sounds is this: Imagine listening to a dynamic sounding (DS) DAC with excellent detail retrieval and very good soundstaging. Now deepen the soundstage, bring faint micro details forward, and add more accurate timbre and decay. Now also imagine that regular PCM sounds as musical as giant DSD files, all without the harshness or fatigue exhibited by many other DACs.

    I imagine many of the these audible improvements to be universal among ladder DACs. I’ve read similar impressions to my own regarding other said designs. Most seem to be a huge leap (or rededication) towards less digital sounding computer audio. I look forward to further advances but am more confident in my desktop’s future with the dac1101 in place. For now, as to the inevitable questions about which ladder/R2R/multibit DACs sound best, I ask: Do you prefer your audio shaken or stirred?

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