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Meier Audio Corda Soul

Corda Soul

  • Introduction

    TL;DR: the Meier Audio Corda Soul is a SOTA, TOTL DAC, headphone amp and line stage with unique engineering features that make it the most transparent and true to the source that I have heard. I recommend contacting Jan Meier to listen for yourself.

    I’ve used an Oppo HA-1 as my DAC, preamp and headphone amp for nearly 4 years. I love its clean neutral sound, driving HD-580 and LCD-2 Headhpones, and my Magnepan 3.6/R speakers. Yet I wonder whether better sound could be had. The Oppo is primarily designed as a headphone amp; its linestage, while very good, is a secondary feature. I listen on speakers at least as much as I do on headphones, and my speakers are more transparent than most headphones. Also, the Oppo's volume control is a potentiometer; a high quality Alps, but still not the ultimate in transparency and perfect channel balance that a well implemented stepped attenuator can provide.

    I discovered Meier Audio 4 years ago when I bought his Jazz amp to replace my aging Headroom Maxed Out Home (which replaced a Wheatfield HA-2). They're both fine amps, but I find the Jazz cleaner, more neutral and refined. And it has some nice features, like a stepped attenuator volume control, selectable image cross-feed and balanced ground drive. It’s hard to find anything this nice for twice the price, and the build quality is great. Meier offers some of the best bang-for-the-buck value I've seen.

    So when I heard that he recently built a SOTA DAC/headphone amp/preamp called the Soul, I was intrigued. The Soul has come out with some anticipation in the headphone audiophile community. I read that Jan brought the Soul to CanJam in Europe and Headfonia elected it "best in show". Given some of the very nice (and expensive!) gear there, and the experienced critical listeners, that says a lot.

    The Soul is not yet in production; as of Jan 2019 it's just about to be released. Jan built 2 Soul prototypes, each of which resembles a science project but is solid, if not elegant, and electrically and sonically equivalent to the production unit. If you contact Jan, you can arrange to borrow the prototype. Jan has a generous policy of not charging to borrow it (though you have to ship it back to him in Germany), and he has a 14-day return policy for the final product.

    It may seem unfair to compare the Oppo with the Soul, as the latter will probably cost several times as much. But the Oppo is what I have, and I’ve always believed, based on comparison with other headphone amps and DACs, that it punches well above its weight class. Also, my goal was not a head-to-head comparison of these 2 DACs, but rather to find out whether the Soul would be a relative improvement. That is only a subtle distinction, but to me an important one.

    Two weeks later, just before Christmas, the Soul arrived at my door having crossed an ocean, a continent, and customs inspectors. I carefully unpacked it, connected it to my system, zeroed all the knobs and made a quick function test. Music! Success! I swallowed my anticipation and left both it and my Oppo HA-1 powered on overnight for listening sessions the next day.



    Before diving into the listening observations, let me summarize a few things:
    • Both are a DAC, headphone amp, and preamp.
    • Both accept Toslink, Coax, USB and analog inputs.
    • Both operate natively in balanced mode (technically speaking, the terms “balanced” and “differential signalling” are two different things–often, but not always, used together. I use the word “balanced” to mean both, as is commonly done in audio circles).
    • Both are well engineered and built.
    Functional Differences: Summary
    • The Soul has DSP features; Oppo doesn’t.
    • The Oppo has additional inputs and outputs that the Soul doesn’t have.
    Functional Differences: Details
    • Oppo has both balanced and unbalanced inputs and outputs; Soul is balanced only.
    • Oppo has Bluetooth input, Soul doesn’t.
    • Oppo has AES/EBU digital input, Soul doesn’t.
    • Oppo has mobile USB input (Apple only), Soul doesn’t.
    • Oppo USB input accepts PCM and DSD, Soul is PCM only.
    • Oppo handles sample rates that Soul doesn't: 176.4k, and rates above 192 k.
    • Soul has multiple digital inputs (3 toslink, 3 coax), Oppo has only 1 each.
    • Soul has DSP features: selectable reconstruction filter, EQ, channel mixing, etc. Oppo doesn’t.
      • Note: the Soul's analog input bypasses these DSP features
    • Soul has digital output (to use its DSP with another DA converter), Oppo doesn’t.
    • Soul has a high (120 Ohm) impedance headphone output — in addition to a standard low (< 1 Ohm) impedance output. Jan describes the reason here.
      • The low Z output is used with most headphones, especially high impedance and planar magnetics.
      • The high Z output can dampen oscillation (e.g. tame a “hot” response) for certain headphones having low impedance.
    Other Equipment
    • Disc player: Oppo BDP-83 playing CDs and DVD-Audio
    • Toslink and Coax PCM output direct to DAC
    • Music recordings with varying bit rates from 44-16 to 192-24
    • Headphones
      • Audeze LCD-2 Fazor, version 2016 upgraded drivers
      • Sennheiser HD-580 with fresh ear & headband pads
    • Speakers
      • Adcom 5800 amp
      • Magnepan 3.6/R speakers
      • Tuned listening room (floor to ceiling tube traps, acoustic foam, etc.)
    Listening Configuration
    • All Soul DSP features disabled and standard linear phase sinc(t) antialias filter used.
    • Both Oppo & Soul left ON all week to ensure they were fully warmed up and stabilized.
    • The Adcom 5800 powered off at night (it draws 250 W idle), but on for at least 30 minutes before each listening session–long enough for the fans to be running.
    • Headphones: the Soul’s low Z output; the Oppo’s balanced output.
    • Speakers: both Oppo and Soul, XLR output to amp.
    • Level matching
      • All comparisons level matched within ½ dB.
      • White noise, equal energy all frequencies, used for level matching.
      • Matching done subjectively by ear, then confirmed and fine tuned with an SPL meter.
    NOTE: My setup is a bit unusual, in that my speakers in combination with the carefully tuned listening room are higher resolution than most headphones. Normally, good headphones are more resolving than good speakers. So my observations and conclusions may also be a bit unusual.

    Listening Notes

    I have omitted several days of detailed notes, which recordings and tracks, and individual observations. Anyone who wants to punish himself reading that kind of detail, contact me. To summarize, musical selections were mostly acoustic music, both small & large ensemble, spanning ancient, renaissance, baroque, classical to modern. Also solo works and good amount of Jazz and Blues, and a small number of rock tracks. Recordings were a mix of CDs and high bit rate downloads from places like HDTracks and Hyperion that I burn to DVD-A to play on the disc player.

    Continue to part 2.
daytona98, jokostyle and FritzS like this.

Recent Reviews

  1. Richter Di
    One Soul to reveal the depth of the music
    Written by Richter Di
    Published Feb 2, 2019
    Pros - Endgame DSP, DAC and headphone amp in one box, pure musical transperency, makes you existing headphones better with a notch filter to kill the strongest resonance frequencies
    Cons - You might need to re-cable some of your favorite headphones

    Sometimes the name of a product reveals so much more. This is the case with the “Soul”.

    I have known Jan Meier now for quite a while. If I am not completely wrong since 2004/2005, when I ended up organizing the first Netherlands Headphone Meet. Over the years I had the chance to try out many of his headphone amps and DACs and also owned and own a few of them. I have observed Jan from the distance designing his new products and often had the chance to listen to the prototypes. But I have to be honest, never have I seen him work so long and with so much passion on a project comparable to the “Soul”. The “Soul” was one where he really took his time to get every detail right.

    But one step after the other. In all the inventions Jan Meier made over time, the “ff” or “frequency-adaptive-feedback” technology was for sure one of the biggest ones, at least for me. I know many are raving about his perfect Crossfeed implementation, and while I see that it has its use, I did not realy need it. But his “frequency-adaptive-feedback” techology brought so much more transparency into my music listening that I am very thankful. Such a genius technology.

    So when the Daccord DAC and the Classic became available with “ff” I ordered both and was in audio heaven. Honestly, after optimizing some digital and audio cables, I thought, this is it. It can not get better than this and I even started selling of my other headphone amps from other companies.

    One day Jan showed up (I live conveniently on his travel route back home to the Netherlands, so he sometimes stops by to say hi) and he had hard wired connected the DAC output of his Daccord with the amp section of the Classic. So while they where still two units he just avoided a lot of inbetween pathway and circuits. He left this strange looking Siamese Gemini with me for 2 nights while he was in the Netherlands and wow, this was again a huge difference in blackness. Voice and music just appeared in the darkness of the night. It gave me chills.
    I couldn’t believe what a difference the “melting” of the two units already meant.

    This also as consequence was his switch to balanced because the signal from the DAC was balanced and to keep it is in its purest form, it meant to also go balanced in the output. I had many discussions with Jan over the years about this topic, and for a long time he was clear that with his “active balanced ground driving” technology there was no immediate need to ask headphone enthusiasts to get their cans recabled. But when he decided to create the best DSP/DAC/AMP unit he could, he switched to balanced without looking back.

    But this was still just the start of his journey. Over the months and months whenever we talked about the “Soul” I was surprised that there was so much more he was building into this endgame machine. I guess the use of a DSP and programming of a DSP was also something new for Jan. But it allowed Jan to take one step of his “ff”-techology to the digital realms. Anothe important milestone to more transparency.

    Under the hood:


    Jan presented one of the new features of the Soul to me one day with his latest prototype, which looked already quite similar to the current layout of the switches etc. We all know that our headphones have a certain resonance frequency or spectrum, which some find very troublesome and others do not care so much about. Extremly famous is the Sennheiser HD 800 6kHz peak which drove Tyll Hertsens - former innerfidelity - nuts. Many mods were created by the community and finally Sennheiser created a 2.0 model - the HD 800s - which comes with Helmhotz resonator included.
    Would we have had Jan’s Soul a bit earlier, this might have not been necessary. The built in 6 dB notch filter of the Soul allows you to dampen very effectively a very small frquency region without otherwise changing the sound.

    Only when you are freed of a resonance you can value how much better the overall quality of the sound becomes. I have to be honest, I am no Tyll, I wouldn’t have figured out why the HD 800 was a headphone I found great but used very seldom at home, although it one of my most comfortable headphones. But suddenly with the peak gone, you have much more relaxed sound. Using the innerfidelity measurements one can do this too for other headphones and yes, the result is pretty astonishing.

    Thanks to Jan I could test the Soul prototype also in his latest stages for over a week with different sources to drive the Soul. While the computer worked phantastic, my tries with iPad pro etc. via the apple camera adapter where not that promising. Seems that the Apple product does not output bit perfect. Make sure you use the Soul with a device offering he digital signal unchanged. Quite important.

    With so much cleaness in the sound coming from the ff-techololgy being digital first, the notch-filter, the complete balanced design and so much more, you have to readjust your listening. Music does not sound like it sounded before. And the brain takes a while to re-adjust but this goes quickly and then the joy of having found a new level of listening will stay for a long time.

    Can’t wait receive my “Soul” soon which will stay with me.
      daytona98 and MRC001 like this.


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