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:
Functional Differences: Summary
- 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: Details
- The Soul has DSP features; Oppo doesn’t.
- The Oppo has additional inputs and outputs that the Soul doesn’t have.
- 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.
- 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
- Audeze LCD-2 Fazor, version 2016 upgraded drivers
- Sennheiser HD-580 with fresh ear & headband pads
- Adcom 5800 amp
- Magnepan 3.6/R speakers
- Tuned listening room (floor to ceiling tube traps, acoustic foam, etc.)
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.
- 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.
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.