Ayre Acoustics Codex headphone amplifier / DAC / preamp


100+ Head-Fier
Pros: Intensely musical and articulate. Outstanding smooth treble that matches well with the HD800
Cons: No analog input, no coaxial or AES/EBU digital inputs, finite power capacity with the HD800, lack of DSD256 support, and no stated plans for MQA
I have had my eye on the Ayre Codex ever since I saw Jude’s review of it on Head-fi TV. Ayre’s high-end credentials in both the DAC and amp space are impeccable, with iconic products like the QB-9 DSD, but this is their first foray into the headphone amp space, and quite frankly, into this low a price point. ($1795)
Similarly, I have had my eye on the Sennheiser HDVA 600, due to it’s beautiful design, and the excellent reviews it’s been getting.
My Objectives
I have been searching for the ideal DAC and amp to complete my system, which is bookended by the Auralic Aries Mini streamer/DAC as the source, and the Sennheiser HD800 (with Anaxilus mod) as the transducer. I had found the Aries Mini’s DAC surprisingly nice, and so have been wondering which system combinations would be right for me within a budget of ~$2000:
  1. Use the Aries Mini’s own DAC along with an amp like the Sennheiser HDVA 600
  2. Use a DAC/Amp like the Codex, the Moon 230HAD, NuPrime DAC-10H, or the Questyle CMA 600i
  3. Use a separate DAC and a separate headphone amp. This could get pricey!
While I have not come even close to comparing all these options, I was fortunate to have a long weekend with both the Ayre Codex and the Sennheiser HDVA 600 gracing my rig. Many thanks to Casey McKee of Ne Plus Ultra in Austin for the Codex loaner, along with some assorted high-end cables. This review covers my impressions of the two pieces in my system. I had already had several weeks to acclimate to the HDVA600/Aries Mini combination, so that was my baseline. I should also mention that all the gear - listed in the System Description section below - had been burned in for several hundred hours, so nothing I heard should be attributable to insufficient burn-in.
What I expected to hear
Based on reviews I had read, I completely expected the Codex DAC to be outstanding. More unclear to me was how the Codex would fare as a headphone amp - especially against a dedicated amp like the HDVA 600 that is acclaimed to match well with the HD800. Needless to say, what I expected to hear and what I actually heard were completely different. 
Sonic Impressions
The music I used in my listening is listed in an appendix below.
My baseline system for several weeks had been the Aries Mini streamer+DAC feeding the HDVA 600. The HDVA 600, in turn, had replaced a Benchmark DAC-1 HDR, which had been doing duty as a pure headphone amp. Compared to the Benchmark, the HDVA 600 elevated the sound quite remarkably. Once burned in, the HDVA 600 had a rich, warm palette with excellent articulation. I could see why it was such a good match with the HD800. By warm, I mean a pleasing solidity in the lower registers, and the midrange had a sweetness that was lovely. But it was in the treble that the HDVA 600 really shone compared to the Benchmark. Where the DAC-1 could make all but the best recorded music sound quite harsh, the HDVA 600 removed that etchiness remarkably. Most impressive about the HDVA 600 was the prodigious amount of power on tap. Even with the input gain on the back set at 10 o’clock, I rarely had to dial the volume above the 50-60% mark.
Several upgrades happened after the HDVA 600 was in place, and each step (replace stock power cables, Black Dragon headphone cable, balanced mode) yielded a small but noticeable improvement.
How ironic then that the addition of the Codex yielded improvements over the HDVA 600 that could be described in very similar ways! In the optimal configuration:
  1. Aries Mini —> Cardas USB cable  —> Codex DAC/amp —> balanced Black Dragon cable —> HD800
the Codex was a revelation. I could not believe how much it further improved over the gains I had previously made with the HDVA 600! There was a feet-tapping rhythmic “rightness” to the music. Maybe this is what people mean by PRAT. It’s hard to describe, but I heard it. Instruments were much easier to isolate because there was more air around them. The soundstage was much larger. And finally, the tonality. I would still give the edge on the low bass to the HDVA 600. The HDVA 600 was no slouch on the midrange either, but I felt the Ayre added an almost liquid character that was beguiling. However in the treble, just like the improvement of the HDVA 600 over the DAC-1, the Codex completely outclassed the HDVA 600. Until I heard the Codex, I had been rather pleased with the HDVA 600. With the Codex, I realized how much more relaxed and, yes, airy - or is it Ayre’y - the high notes sounded. Astoundingly, I found myself describing the HDVA 600’s treble as edgy and harsh. The difference was most apparent on music with tambourines (Cossack Dance), cymbals/high hat (Take Five), brass (Mahler’s 5th), but was apparent on every piece.
My final test was to have my emphatically non-audiophile wife - who is ironically blessed with golden ears :) - have a listen. She reinforced my opinions in about 10 mins. After listening to Why Worry by Dire Straits on the Codex, she declared it to be a goose-bump inducing experience, the best she had ever heard. In fact, after that she found the HDVA 600 “unlistenable,” which is terribly unfair to such a great piece of gear. 
This is the irony of high-end audio. Sonic differences in gear can be small, BUT - once heard, going back is really hard!
So how much of the overall differences I heard can be attributed to the Codex’s DAC versus it’s headphone amp? To attempt to answer that, I did two comparisons:
  1. Amp comparison - Hold the DAC constant - use the Codex - and compare these two setups
    1. Codex —> Black Dragon balanced cable —> HD800
    2. Codex —> Cardas XLR interconnects —> HDVA 600 —> Black Dragon balanced cable —> HD800
  2. DAC comparison - hold the amp constant. Since only the HDVA 600 has multiple analog inputs, I had to use it as the amp, and compare the following
    1. Aries Mini —> RCA interconnect (single ended) —> HDVA 600 —> Black Dragon balanced cable —> HD800
    2. Aries Mini —> Cardas USB cable  —> Codex —> Cardas XLR interconnects —> HDVA 600 —> Black Dragon balanced cable —> HD800
Amp Comparison
Essentially all the differences I described above in the overall section were evident even if I used the Codex DAC into both amps. This just floored me. I was not expecting the Codex to be such a better sounding amp. I should reiterate the superior low end of the HDVA 600. Also, maybe it’s because I like to listen to my HD800’s rather loud, but on some classical pieces, I was dialing up the volume on the Codex to >95%. This could mean with some particularly inefficient cans, the Codex may not have enough power. For me, with the HD800, I tried enough music from my collection to feel satisfied that I wouldn’t have that issue, but it could be a concern.
DAC Comparison
Here again, I had a surprising finding. I found it extremely hard to tell the Codex apart from the Aires Mini. This too was unexpected - I expected the Codex to smoke the Aries Mini. Perhaps the HDVA 600 was limiting the DAC differences. I don’t know. Since the Codex didn’t have any analog inputs, we’ll never know if the differences in the two DACs would have been more noticeable with the Codex as amp. This to me is the other limitation of the Codex - the lack of an analog input. In any case, I had nothing better by way of amps to do this DAC comparison.
The Codex is an outstanding DAC/amp, especially at its $1795 price. I could easily see it as an end game DAC/Amp solution for a large segment of headphone users. It may even be the end game solution for me. It does have some limitations: no analog input, no coaxial or AES/EBU digital inputs, finite power capacity with the HD800, lack of DSD256 support, and no stated plans for MQA. Maybe future Ayre products will address these things. Ayre has a pretty good track record of doing right by its customers to provide upgrade paths where possible. If these limitations are not showstoppers, you owe it to yourself to audition the Codex.
System Description
  1. Source:                            Auralic Aries Mini network streamer, with Auralic LPS
  2. Music server:                   Synology DS213 NAS, running MinimServer 
  3. DACs under test:             Aries Mini built in DAC, Ayre Codex
  4. Head amps under test:    Sennheiser HDVA 600, Ayre Codex
  5. Headphones:                   Sennheiser HD800 with Anaxilus mod
  6. Cables
    1. Headphones          Moon Audio Black Dragon Premium HD800 balanced 4-pin XLR
                                        Black Dragon adapter 4-pin-XLR to 2x3.25mm balanced (for adapting to Codex)
    2. Interconnects         Cardas XLR (older generation from current Clear)
                                        Kimber PBJ RCA
    3. USB                       Cardas (not sure which one)
    4. Power                    Pangea AC-9 MkII, AC-14SE MkII
  7. Power conditioner           PS Audio Dectet
Music Selections
  1. Mahler - Symphony No. 5, 3rd movement, Benjamin Zander, Philharmonia Orchestra, Telarc, DSD64
  2. Dire Straits - Why worry, Brothers in Arms, Mobile Fidelity DSD64
  3. Tchaikovsky - Cossack Dance from Mazeppa, Erich Kunzel, Cincinnati Pops, Telarc, DSD64 and 24/44.1 PCM
  4. Dave Brubeck - Take Five, Time Out, Analogue Productions, DSD64
  5. Ottmar Liebert - La Luna, Up Close, 24/96 PCM binaural
  6. Talvin Singh - untitled piece #2, Accidental Powercut 3, B&W Society of Sound, 16/44.1 PCM binaural
  7. Yes - The Revealing Science of God, Tales from Topographic Oceans, 24/192 PCM
  8. Supertramp - School, Crime of the Century, 24/192 PCM
  9. Buena Vista Social Club - El Cuarto de Tula, 24/96 PCM
  10. Berlioz - Harold in italy, 3rd movement, Gergiev/LSO, 24/96 PCM
Excellent comparative review. Hope I'll get a chance to have an audition of the Codex soon.
@REXNFX, let me clarify.
She was comparing
        a) Mini --> USB --> Codex --> XLR --> HDVA 600 --> HD800
        b) Mini --> USB --> Codex --> HD800.
So her comment was in the context of the amp comparison in my review. Hope that clarifies things.
Got it, Thanks!


1000+ Head-Fier
Pros: Stunning midrange purity, addicting musicality
Cons: Case gets fairly hot
First off, thanks to Tom at Gifted Listener Audio for loaning me the Ayre Codex for a weekend.
Ayre Acoustics is one of those companies in the hi-fi audio world that really needs no introduction yet it seems they've been curiously absent from the head-fi scene. The QB-9 USB-based DAC was a forward-thinking foray into computer-based audio, but since then it's been mostly radio silence on anything headphone-related, that is until their recent collaboration with Neil Young on the Pono. That particular pairing is what brings us to the Codex. This diminutive black box marries Ayre's expertise in full-size audio electronics with their knowledge gained from designing the innards of the Pono to give us a flexible piece of kit that can serve as a headphone amp, DAC, and preamp.
The Codex eschews the audiophile preoccupation with fancy casework, all presumably to keep costs down in order to focus more resources on what matters most - the electronics. At the heart of the Codex is the same fully balanced, zero feedback diamond topology1 found in Ayre's top-line 'R Series' and the more mainstream '5 series' integrated amp and separates. Volume control is handled in the digital domain without any loss of resolution. The DAC section can accept PCM data up to 24-bit / 384 kHz as well as DSD64 and DSD128. The wizards at Ayre even managed to fit a linear power supply in the chassis. Nice.
The front panel is slightly longer than the rear which gives the entire casing a gentle upward slope. From top to bottom on the front faceplate is a red multi-segmented LED display window, a multi-function knob for volume control and menu navigation, a red LED to indicate balanced mode, two 3.5 mm headphone jacks, and a single 1/4 inch headphone socket at the bottom. The rear has both single-ended and balanced analog output as well as inputs for USB (full size type B) or optical connections. A small power rocker switch turns everything on or off. A USB cable and power cord are included.
A possibly frustrating quirk is that the 3.5 mm output jacks are recessed about 1/8" from the surface of the front panel within the center of a circle about 1/2" in diameter. This may cause some plugs with oversized barrels to either not make full contact with the jack or prevent both jacks from being used at the same time.
There are some operational intricacies to be aware of. When both 3.5 mm outputs are connected, the LED display flashes 'Bal' for balanced mode. If the knob is rotated once, then 'Shr' flashes on the display to indicate single-ended shared listening mode. A press of the knob activates the selected mode. If the balanced option was activated, the red LED below the volume knob will light up. However, if a headphone is connected to the 1/4" output, then balanced operation is not possible, regardless of whether both 3.5 mm outputs are connected. Plugging in headphones into any jack will also automatically enable the volume control, even if the Codex is in standalone DAC mode. Note that the manual contains several reminders to never connect the balanced analog outputs on the rear panel to single-ended equipment or damage to the Codex will result.
Entering into the setup menu requires one to push and hold down the volume knob until the LED display starts flashing. Rotating the knob scrolls through all the menu options while a single short press of the knob selects the current option.
One word of caution - the case gets fairly hot after you've been using it to drive headphones, but curiously not so much when running in DAC mode. It's not like grabbing a cast iron pan off a hot stove without a mitt kind of hot, but it can get uncomfortable if held in the hand for any period of time. (Not sure why you'd want to do that though.) A plus is that the volume knob doesn't seem to heat up a la Home Alone like the Schiit amps I've encountered.
I first listened to the Codex with my Sennheiser HD 600's wired for balanced drive with SurfCables' robust P-01A (20 AWG version), using my laptop as a source and connected via USB. The sound was incredibly smooth yet detailed, warm, and natural. The Codex seemed to extract more information from Red book standard data than I thought possible. A good example was the final movement from Rachmaninoff's Second Piano Concerto as performed by Earl Wild and the Royal Philharmonic Orchestra (Chesky, CD 2). Piano had no trace of overhang or clanginess. Rather, it possessed a solidity to the sound that came in the form of more tone from the instrument. This wasn't artificial bloom either - it was clean, pure tone that gave each note a lifelike quality. This didn't intrude one iota on microdynamics - the Codex allowed me to easily follow the flurry of inner notes rising and falling with Wild's expressive touch on the keyboard. Massed strings were reproduced with a remarkable ease that reminded me of live performance. Coltrane's sax on "I'm Old Fashioned" from Blue Train (Blue Note, 53428) had a lovely, burnished glow that didn't mask the inner detail of the brass nor his subtle tonal inflections. Once again piano sounded delectable - Kenny Drew's solo reproduced with just the right amount of tone and touch. The Codex seemed to just let the music flow from the headphones.
The Codex's pure midrange also served it well on more modern fare. Vocals in particular were rendered with clarity and realism. On "1234" from the album The Reminder, Feist's voice sounded corporeal and immediate. Snare drums had good body as well as impact. Even hand claps sounded more realistic - I could distinctly hear the tone of two fleshy palms being suddenly slapped together instead of just a sharp transient. The Codex also brought this level of realism to The National's performance on "Bloodbuzz Ohio" from High Violet (4AD, CAD 3X49 CD). The bass line had fine texture and weight. Berninger's voice projected out over the mix, full-bodied and communicating abject forlorn. Cymbals had a brassy sheen to them instead of a tizzy sizzle. I was intrigued to find out how it would handle Florence + the Machine. I love the music, but I find most of her albums bright sounding which on poor systems results in an aural sensation not unlike that of fingernails being dragged across a chalkboard. The Codex sailed through with flying colors. It portrayed Florence Welch's vocals on "Ship to Wreck" from How Big, How Blue, How Beautiful (Republic, B0023122-02) with such composure and grace that I couldn't help but smile. Pipe organ on "Shake It Out" from Ceremonials (Republic,
B0016297-02) was steeped in​
sonorous harmonic texture. Each performer seemed to be delicately layered within the track.
The Codex was no slouch in single-ended mode either. Listening with the HD 600 in its stock form and the Etymotic ER-4S in-ear monitors still yielded an exceptionally emotionally engaging, organic presentation. There remained a distinct sense that real, live human beings were performing instead of reasonable facsimiles. Perhaps there was a slight loss in clarity, but I wouldn't run too far with that statement.
Ayre vs. Ayre
Since the Codex can also function as a standalone DAC, I was curious how it would stack up against a more specialized machine - in this case Ayre's own (discontinued) C-5xeMP universal stereo disc player. I disconnected the balanced interconnects from the C-5xeMP and snapped it into the rear of the Codex. I played a few tracks from the laptop to make sure everything was working properly. Then I cued up "I'm Old Fashioned" for a little cage match. In terms of tonality, the Codex didn't disappoint - it remained warm, relaxed, and wholly inviting. However, next to the C-5xeMP's more vibrant personality, I felt the Codex gave up just a smidge in the resolution department. It also didn't throw as wide or deep a soundstage as the disc spinner. My only caveat here is that my time with the Codex at this point was nearing the end, so I didn't get to explore this facet of performance as completely as I wanted to. I'd say it's a good excuse to get some more time with the Codex in my system.
Unfortunately, my system setup also precluded me from experimenting with the preamp function. (My current integrated amp doesn't have a separate power amp input section.)
Ayre vs. Schiit
(Note, this section was added after the original review was published to add some more perspective. Plus, I like to use the word 'Schiit'.)
I don't personally own any gear from Schiit, but I have heard their products several times at Head-Fi meets. Although a direct comparison against a competitively priced Schiit stack (Mjolnir 2 + Gungnir Multibit) is currently out of the question, I will, somewhat hesitantly, offer up some general impressions of how I think the Codex fares. My most recent encounter with Schiit was a few days ago from the time of this writing at a Head-Fi meet with two separate systems - HE1000 + Ragnarok + Yggdrasil and HD 600 + Valhalla 2 + Bifrost Multibit. I found the Schiit house sound to be quite neutral and revealing, which reminded me of how Bryston voices their products. Though I can certainly appreciate this sort of presentation, I find it somewhat emotionally distant. The Codex, by contrast uses a warmer tonal palette. I also found the Codex to have a unique quality about its midrange that imparted an uncanny realism to performances that captured my attention completely. To use an audiophile cliche, there was more there there. Though I know great debates rage on about circuit topologies and DAC architectures, I find that the proof is in the listening. In my mind, I think the Codex can compete quite favorably here, even with Schiit's top of the line.
The Codex may not be the most flashy piece of gear to grace a desktop, but it truly delivers the goods where it counts. It's almost as if they shrunk an AX-5 Twenty to power headphones. That's a phenomenal sonic and technical achievement and all the more impressive since its siblings tend to cost at least an order of magnitude more. In a world where some hi-fi components do an excellent job at reproducing sound, I feel that the Ayre Codex is built to make music and deserves a place at the top of anyone's shortlist. Very highly recommended.
Associated Equipment
Headphones - Etymotic ER-4S, NAD Viso HP50, Sennheiser HD 600
Loudspeakers - Vandersteen 3A Signature
Amplification - Ayre AX-5 Twenty, Meridian Explorer 2
Sources - Ayre C-5xeMP, Meridian Explorer 2
Cabling - Analysis Plus - Solo Crystal Oval 8 speaker cables; Pro Oval Studio balanced and Copper Oval-In single-ended interconnects; Pro Power Oval, Power Oval 2, and Power Oval 10 power cords, SurfCables - P-01A balanced cables for Pono (20 AWG)
Power - Bryston BIT-15, AudioQuest JitterBug
1. http://audioasylum.com/forums/amp/messages/18/185962.html
NA Blur
NA Blur
Wonder if Ayre would send one to Tyll to measure?
Well written review yage. I couldn't help but think I was reading a stereophile review it was that good. Thanks for the good read.