Recommended Components

A+

ampsandsound Bigger Ben: $5600
See "Integrated Amplifiers."

Dan Clark Audio Stealth: $3999
The Stealth weighs 415gm and presents a low (23 ohm) impedance and a low (86–87dB/mW) sensitivity. HR was impressed by these closed-back, planar-magnetic headphones, which feature a patent-pending Acoustic Metamaterial Tuning System (AMTS)—an intricately formed, waferlike partition situated between the driver diaphragm—and the deeper-than-average ear cavity. He wrote that the Stealth's sound was "clear, finely detailed, and extremely well-balanced" though he also noted that it was also "somewhat distant," lacking some high-frequency directness compared with the HiFiMan Susvara open-back planar-magnetics. However, he found that the Stealth's upper bass and lower midrange were tauter, fuller, and more vividly portrayed than the Susvara's, a balance that worked well with female vocals. He concluded that the Stealth's most prominent virtues were its comfortable fit, its extraordinary build quality, its elegant way with detail, and its marvelously balanced, low-fatigue presentation. (Vol.45 No.7 WWW)

dCS Bartók: $22,950 incl. headphone amp; $20,950 without headphone amp
See "Digital Processors."

HiFiMan Susvara: $6000 ★
The HiFiMan Susvaras are over-the-ear headphones with planar-magnetic drivers, built around gold-coated Nanometer Grade diaphragms—their thinnest ever, the company claims. The drivers also use HiFiMan's Stealth Magnet grids, the individual magnetic strips of which have rounded edges to reduce interference with sound output. The Susvaras weigh 15.9oz and offer an impedance of 60 ohms and a sensitivity of only 83dB. HR later wrote that he thinks the Susvara is a contender for the world's best headphones. However, when he auditioned the Susvaras with the LTA Z10e amplifier, he found that, with the combination of low impedance and low sensitivity, the Susvara needed more power than the amplifier could deliver. Subsequently though, that amplifier was updated to provide its full available power—10Wpc—to headphones. (Vol.40 No.12, Vol.43 No.5, Vol.45 No.7 WWW)

JPS Labs Abyss AB-1266 Phi TC: $5995-$8995 ★
For those who regard the JPS Abyss AB-1266 Phi headphones as prohibitively expensive, HR offers perspective, suggesting that they, like such "notorious legacy products" as the Wilson Audio WAMM loudspeaker of 1983 and the Audio Note Ongaku amplifier of 1993, "exist in categories of price and performance all their own." The Abyss 'phones are built into black-anodized aluminum frames and use single-magnet planar-magnetic drivers separated from the wearer by rotatable lambskin earpads held in place with magnets. Specs include a sensitivity of 88dB and an impedance of 42 ohms. After listening to a Schoenberg piece through the Abysses driven by the Woo WA5 headphone amp, HR reported: "I scribbled the phrase 'perfectly natural' several times. I never felt more kindred or connected to Schoenberg." He also suggested that the Abysses "delivered detail and soundstage images with an uncannily visual—nay, infinite—depth of field." HR later wrote that "The amazing part of the Abyss Phi TC 'phones is their complete absence of diaphragm breakup or modulation noise: They are the quietest speaker drivers I've ever heard. With the right amp, the AB-1266 'phones feel like they strip everything away between me and a recording." (Vol.40 No.8, Vol.43 No.5, Vol.44 No.10 WWW)

Meze Audio Elite: $3999
The planar-magnetic drivers used in these open-back headphones feature a proprietary diaphragm/magnet assembly that Meze calls an "Isodynamic Hybrid Array." The ultrathin, biaxially oriented, semicrystalline polymer diaphragm weighs only 0.11gm and is driven by two driver coils to give a specified sensitivity of 101dB/mW with an impedance of 32 ohms. The Elite comes with two different earpads, one leather, the other made from a hybrid material and with a higher volume chamber. Despite the hybrid pads eliminating a slight bloom that shadowed the lower midrange with the shallower, all-leather pads, HR preferred the leather pads because he revels in "deep transparent spaces and luminous darknesses." Compared with his reference RAAL ribbons, the Meze sounded "smoother, more nuanced, kinder to singers, and easier on the mind." Compared with the Dan Clark Stealth headphones, the Meze Elite "did a better job transmitting the subtler aspects of vocal and instrumental tone and allowed vocalists to sound more like themselves." (Vol.45 No.9 WWW)

Raal-requisite SR1a: $2900
With Ribbon amp interface: $3500
Described by HR as headphones that will satisfy "headphone connoisseurs and stubborn contrarians" alike, the off-the-ear RAAL-requisite SR1a's have a physical design that prevents them from covering or putting pressure on your pinnae: Their sound character is not determined in any way by a padded acoustical chamber around the listener's ears. Electrically, the SR1a's are built using open-baffle ribbon drivers, the very low impedance of which force the need for an impedance-matching box (included) and a 50–150Wpc loudspeaker amplifier (not included). Herb had his best results driving the RAAL-requisite 'phones with solid state amps and said of the SR1a/Pass XA25 amp combo, "No matter what hi-fi you have, it's unlikely to dig deeper and find more beauty in your recordings." When he tried the SR1a's with the Schiit Jotenheim R amplifier, HR commented that "The more I've used the SR1a, the more I've realized they reproduce recordings with unprecedented levels of musical texture and tactility" and concluded "No headphone images anywhere near as accurately or spectacularly as the SR1a, period." (Vol.43 Nos.1 & 7 WWW, Vol.44 No.10)

Stax SR-X9000: $6200
This electrostatic headphone uses a diaphragm made from ultra-thin engineering film and is 20% larger than that of the previous Stax flagship, the SR-009S. Driving the Stax with Linear Tube Audio's Z10e amplifier, HR found that the soundspace the headphones generated "was full and complete, perfectly mapped, and cram-packed with delectable detail." With the same amplifier, he found that the SR-X9000 played very slightly brighter, more upfront, more distinctly detailed, and a tiny bit more physical than HiFiMan's Susvara planar-magnetic openbacks. "The Stax's upfrontness made the Susvara sound darker and deeper-spaced, more misty-humid than I usually perceive it to be," he wrote. With both the Z10e and Woo's 3ES amplifiers, HR concluded that the SR-X9000 "displayed greater microscopic resolution than every other transducer I have in-house including my ultimate reference, the JPS Labs Abyss AB-1266 Phi TC." (Vol.45 No.3 WWW)

T+A Solitaire P: $6900
Made in Germany, the T+A's Solitaire P headphones use a relatively large, oval planar-magnet diaphragm made of "structurally stable High-Tech polymer." Impedance is specified as 80 ohms. Two sets of earpads are supplied: The standard earpads are covered with gray microfiber suede, while the "UWE" earpads use foam that is firmer than that in the standard pads and encased in perforated artificial leather on the inside and microfiber suede on the outside. The UWE earpads are described by the manufacturer as elevating the high frequencies "just enough to add sparkle and detail for those who prefer that type of sound." This was confirmed by HR, though he also felt these earpads lacked the rich harmonic underpinnings he prefers for a satisfying orchestral music experience. With the standard, nonperforated earpads, driven by T+A's HA 200 headphone amplifier, the Solitaire P sounded balanced, with saturated tone and spacious, fluent clarity. HR enjoyed what he described as the Solitaire P's "look-inside-the-recording transparency." (Vol.44 No.2 WWW)

ZMF Auteur Classic: $1499.99
The zebrawood Auteur LTD weighs 490gm, uses biocellulose diaphragms, combines fairly high sensitivity (97dB/mW) with a high impedance (300 ohms), and comes with two sets of earpads. HR preferred the standard, perforated Auteur pads, which he said "generated one of the most delectable midranges I have experienced." He found the Eikon pads emphasized the bass enough to slightly obscure that luscious midrange. (Vol.43 No.4 WWW)

ZMF Vérité Closed: $2499.99
The MonkeyPod-wood Vérité Closed headphones weigh 35gm less than ZMF's Auteur LTDs due to using a magnesium headband rather than aluminum. Offering a sensitivity of 99dB/mW and an impedance of 300 ohms, the Vérité Closed headphones use an "ultra-thin" polyethylene naphthalate driver with a vapor-deposited beryllium coating. Using the standard Universe earpads, bass was tighter and more powerful than HR could remember experiencing with any headphones. "Piano and plucked-bass notes exhibited a very distinct leading edge, followed by an unusually solid note-center, followed by a trailing edge that I perceived as mildly attenuated," he wrote. Replacing the Universe earpads with the Vérité pads made the low frequencies sound perfectly tight and tuneful. "The midrange came up and brought the presence region with it. The 1–8kHz octaves were exquisitely detailed and wide open, he summed up, adding in a Follow-Up that "the Vérité was the Schiit Jotunheim's favorite headphone." (Vol.43 Nos.4, 5 & 7 WWW)

A

Audeze CRBN: $4500
The open-backed electrostatic CRBN—pronounced "carbon"—headphones weigh just 300gm and feature an "uncoated" polymer-film diaphragm infused with carbon nanotubes. HR found that with the Woo 3ES amplifier, the CRBN "resolved deep into the recording like the open-back planar-magnetic Susvara, and like JPS Labs' Abyss AB-1266 Phi TC, but the music . . . was more brightly lit and sharply focused than it is with those venerable magnifiers. With the Audeze, sounds were exquisitely formed, distinctly visual, and exceptionally three-dimensional." He concluded that the Audeze CRBN "distinguished itself by its understated clarity and lack of electrostatic-ness. Together, these traits produced a neutral, natural, high-detail, low-fatigue, listener-friendly headphone experience." (Vol.45 No.1 WWW)

Audeze LCD-X: $1199 (travel case included) ★
These large, luxurious, circumaural headphones have planar-magnetic drive-units with a thin-film diaphragm energized by arrays of powerful neodymium magnets on both sides. They employ Audeze-patented Fazor elements, claimed to guide and manage the flow of sound in the headphone. The circular drivers are housed in polished, black-anodized aluminum earpieces cushioned with generously sized foam pads covered in lambskin or leather-free microsuede. Adjustment is via notched, chromed metal rods attached to each earpiece, which fit into the sprung, leather-clad headband. The LCD-Xes produced a seductive, compelling sound with precise imaging, rich mids, smooth highs, and clean bass, JA said. Compared to his longtime reference Sennheiser HD 650s, the LCD-Xes resolved more detail, produced the more convincing sense of recorded ambience, and provided deeper bass. "Highly recommended!" JA concluded. HR found that the Audezes driven by the Schiit Jotunheim "gave reproduced music life and brilliance." "Creator Special" edition (without travel case) costs $1199. (Vol.37 No.3, Vol.41 No.6, Vol.43 No.7 WWW)

Benchmark HPA4 headphone amplifier: $3299 w/o remote; $3399 with remote
The HPA4 adds a THX888 amplification stage to Benchmark's LA4 line preamplifier (see "Preamplifiers") to allow it to drive even low-impedance headphones with aplomb. It keeps the LA4's balanced and single-ended preamplifier outputs and adds a headphone output on a 4-pin XLR jack and a single-ended headphone output on a 1/4" jack. HR noted that with the hard-to-drive HiFiMan Susvara headphones, the HPA4 "showed each instrument in dramatic bas-relief. It accomplished this by presenting cleaner, better-articulated bass and manufacturing a sharper midrange focus than I had experienced previously with either my solid state reference, the Pass Labs HPA-1, or the tubed Linear Tube Audio Z10e." With the JPS Labs Abyss AB-1266 Phi TCs driven by the HPA4, "deep bass emerged with great volume and energy." "My romantic-dreamer mind adapted surprisingly well to the Benchmark HPA4's presentation," HR concluded. "The more I used the HPA4 to drive high-resolution headphones, the more comfortable I felt with its precise, pro-audio recording-studio aesthetic." JA noted that the the LA4 preamplifier was "the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I had encountered at that time. . . . To those virtues, the HPA4 adds equally superb balanced and single-ended headphone outputs." Optional remote costs $100. (Vol.44 No.2 WWW)

Feliks Audio Euforia: $2699
Built in Poland, the Euforia Mark II is an output-transformerless (OTL) headphone amp that uses 6AS7G dual-triodes as output tubes and 6SN7 dual-triodes as small-signal tubes. The Euforia has a single pair of (RCA) inputs and a single 1/4" output jack. The amp is specified by its manufacturer as offering 130mW into 32 ohms and 200mW into 100 ohms. Herb said the Euforia made the Grado GS3000e headphones sound "more transparent and satisfying" than the other headphone amps he had on hand; he further observed that "the Euforia's radiant liquidity enhanced [the Focal Clears'] sense of flow and resolve." (Vol.42 No.12, Vol. 43 No.4 WWW)

Ferrum OOR: $1995
Class A only when used with Ferrum Hypsos power supply; otherwise Class B. DC-coupled, fully balanced headphone amplifier/preamplifier—single-ended input signals are converted to balanced—with adjustable maximum gain and four-pin XLR and ¼" headphone outputs. Used as a preamplifier, the OOR reminded HR of "a middleweight boxer landing quick hard jabs; in music (not boxing), this quality emphasized tempo changes, plucked notes, and short pauses in the performance stream." Used as a headphone amplifier with JPS Labs Abyss AB-1266 Phi TC 'phones, the OOR reproduced a Huddie Ledbetter recording with the sound of Huddie's voice and guitar "taut, well-defined, and clear as clear can be." Adding Ferrum's HYPSOS supply—see Powerline Accessories—ameliorated some dryness and grayness that had been evident on Ledbetter's voice. HR concluded that the OOR/HYPSOS combo "will drive any headphones effortlessly while preserving the soul and essence of the music they amplify." (Vol.45 No.2 WWW)

Focal Clear Mg: $1499
Focal's Clear Mg headphones replace the original Clear's aluminum-magnesium alloy–dome drive-units with pure-magnesium domes, these ensconced in a chestnut-colored, honeycomb-grilled headset finished in leather, microfiber, and "mixed metals." The new Clear is more clear than the old Clear, decided HR: "the Mg produces a fresh, bell-like clarity that puts my mind closer to and further inside every recording. Reverb has more presence with the Clear Mg. Piano notes have better-articulated attack and decay. Guitar strings are tauter and more vividly described." However, while with every recording HR tried, the new Clear Mg sounded more transparent, more sharply focused, more punchy, and more left-brain precise than the original Clear, on every male and female vocal, the old Clear put him closer in touch with the singer's personality. (Vol.44 No.9 WWW)

Focal Stellia: $2999
When he first heard these closed-back headphones, which use 1.5" M-shaped electrodynamic beryllium-dome drivers and have a 35 ohm impedance, HR felt that they "were delivering a very high level of relaxed and refined sound, with no beryllium metallic-ness." Continued listening with the Feliks Euforia amplifier resulted in "more excitement and colorful energy" than with the Auris Nirvana powering the Focals. HR concluded that with the HoloAudio May DAC and the Euforia, "Focal's Stellia closed-backs produced vital, exciting sound." (Vol.43 No.10 WWW)

Grado Labs GS3000e: $1795 $$$
Grado's flagship "Statement Series" headphones, the made-in-Brooklyn GS3000e, feature 50mm Mylar drivers built with neodymium magnets and present the driving amplifier with an impedance of 32 ohms and a sensitivity of 99.8dB. According to HR, when driven with a complementary amplifier, the Grados impress with their "swaggering rock'n'roll boogie factor," but they can also sound "elegant and refined." As a bonus, the Grados "look and feel more expensive than [their] price would suggest." (Vol.42 No.12 WWW)

HeadAmp GS-X mini Balanced: $1995
The first HeadAmp product to "deliver balanced headphone drive from all sources, single-ended or balanced," the GS-X Mini offers potentiometer or optional stepped-attenuator volume controls and is specified to output 6W of power into a 25 ohm load. HR found that this solid state amplifier made clear the sonic differences between the headphones with which he used it. (Vol.45 No.9 WWW)

HEDD Audio "HEDDphone": $1899
The "HEDDphone" headphones use full-range, air-motion-transformer (AMT) drive-units and proved a synergistic match with the Pass Labs HPA-1 and Feliks Audio Euforia headphone amps, found HR, commenting on "an extraordinary level of transparency." (Vol.43 No.7 WWW)

iFi ZEN CAN Signature: $599 with ZEN DAC Signature V2
Packaged with the ZEN DAC Signature V2—see Digital Processors—this headphone amplifier is available in two versions: the 6XX, which includes equalization to optimize the sound of the Sennheiser x Drop HD 6XX and HD 650 headphones; and the HFM, which has equalization for the HiFiMan x Drop HE4XX 'phones. Apart from the different EQ curves, the two versions contain identical circuitry, and the EQ can be bypassed for use with other headphones. The ZEN CAN also includes iFi's XSpace feature, which is intended to expand the perception of space and project the music outside your head. The amplifier offers four choices of maximum gain, from 0dB to 18dB from the single-ended outputs, 6–24dB from the balanced outputs. JMu found that even with the lowest gain setting, the ZEN DAC Signature's balanced output was too "hot." She found that using iFi's iEMatch attenuating balanced cable ($49) gave a better gain match between the two iFi Signature products, though JCA didn't find the attenuator cable necessary with the same headphones. JMu auditioned both versions of the ZEN CAN with the appropriate headphones. With the EQ, she heard sharper transient attacks, more air and presence, and more detail and clarity, adding that "yes, the EQ curve obviously boosts the bass," which correlates with JA's measurements. JCA found that the effect of the CANs' custom EQ wasn't dramatic, but it was positive, especially with the HiFiMan headphones, which could sound a bit woolly without it. Without EQ, JMu found that "tonal balance with the ZEN set seemed extended and neutral, with rare hints of brightness." JMu concluded that the ZEN Signature sets "offer impressive sound quality—and a bit of style—for not a lot of money." (Vol.45 Nos.1 & 3 WWW)

Linear Tube Audio Z10e: $6950
The all-tube Z10e integrated amplifier/headphone amplifier/electrostatic headphone amplifier is built around a David BerningǾdesigned, push-pull, output-transformerless (OTL) EL84-tube power amplifier that is rated at 12Wpc into 8 ohms and 13Wpc into 4 ohms. "The Z10e is a distilled, shape-shifted version of the Z10, designed to appeal to today's new breed of headphone collector-connoisseurs," HR wrote. It also has a five-pin, 580V-energized output to drive Stax electrostatic headphones. Though he liked how this amplifier sounded with high-sensitivity DeVore and Zu loudspeakers, he mostly used it with a variety of headphones. The Z10e got the best from Abyss AB-1266 Phi TC, Focal Clear, and ZMF Vérité Closed dynamic headphones and excelled with Stax SR-009S and Dan Clark Voce electrostatics. Herb found it wasn't powerful enough to drive the demanding HiFiMan Susvaras, but then it was upgraded to deliver the full 10Wpc to headphones. After the update, it reproduced low frequencies that were "delectably large." HR summed up the revised amplifier by saying, "The LTA Z10e/Susvara combo missed no beats, showed no weaknesses, and kept my head bopping. . . . The Z10e amp displayed no hesitations, dullness, or clipping; no smoke from the tires, no engine stalling—only full-traction, high-torque engagement." With the Audeze CRBN headphones, the Z10e's "overall, timbre and tone were just right and satisfyingly color-saturated." (Vol.43 No.5, Vol.44 No.2, Vol.45 Nos.1 & 3 WWW)

Naim Uniti Atom HE: $3799
The "Headphone Edition" of Naim's Uniti Atom streaming D/A integrated amplifier, the Atom HE features both single-ended and balanced headphone outputs as well as a preamplifier output. Inputs include a single unbalanced analog on RCA and and digital—two TosLink S/PDIF, one coaxial S/PDIF, USB, Ethernet, and Bluetooth (aptX). Control is via buttons next to the front-panel display, Naim's iOS and Android apps, or with Roon. Used as a D/A preamplifier, the Atom impressed HR: It reproduced the body and reverberant character of a piano as graphically and completely as his Rogue RP-7 preamp sourced by the dCS Bartók. "That, folks, is saying a lot," he wrote. With the Atom HE powering the easy-to-drive, low-impedance (35 ohms), high-sensitivity Focal Stellia headphones, HR felt the sound was "squeaky-clean, bass-taut, and superdynamic lively." After five weeks of auditioning the Uniti Atom HE with a variety of headphones, HR concluded that its best and most obvious trait "was how gracefully and insightfully it danced through one musical genre after another. It was never not enticing. It was never not engaging. It never disappointed." However, he did caution that the Atom HE plays best with headphones with a sensitivity of 88dB/mW or higher. (Vol.44 No.9 WWW)

Pass Labs HPA-1: $3675 ★
Also usable as a line-level preamp—it has a pair of single-ended RCA output jacks—the Pass Labs HPA-1 is a perfectionist-quality headphone amplifier that uses a MOSFET-based current-feedback amplifier to drive headphones ranging from 15 to 600 ohms. Its single headphone-output jack, also single-ended, is a Neutrik locking jack sized for ¼" plugs. After auditioning the HPA-1 with a variety of 'phones from Audeze, AudioQuest, and Master & Dynamic, JA declared that "in bass quality and authority, and in midrange transparency, the Pass Labs HPA-1 is without peer." JA also brought the HPA-1 to his test bench, where it stood up to everything he could throw at it (well, not literally), prompting the appraisal: "superb audio engineering." One of HR's long-term reference headphone amplifiers. (Vol.39 Nos.7 & 9, Vol.43 No.7 WWW)

Raal-requisite HSA-1b: $4500
A rating is as a headphone amplifier only. This Serbian solid state amplifier drives both headphones and loudspeakers. With the latter, it's specified to produce 10Wpc into 8 ohms, 20Wpc into 4 ohms, 40Wpc into 2 ohms, and 55Wpc into 1 ohm. It has both single-ended and balanced inputs, a 3.5mm (unbalanced) TRS jack for conventional headphones, and a four-pin male XLR jack for RAAL's SR1a ribbon headphones. HR found that with the SR1as, the HSA-1b delivered a "richer, meatier, more colorful sound" than his Pass Labs XA25. With RAAL's SR1a's and SR728 Silver Headphone Cable, the HSA-1b "represent the cutting edge of what is currently possible in high-resolution audio reproduction," he concluded. (Vol.44 No.10 WWW)

Sennheiser HD 650: $549 ★
The HD 650s are an evolution of Sennheiser's very successful HD 600 open-back dynamic headphones, claimed to provide superior results due to hand-selected parts with closer tolerances and the use of a specially developed acoustic silk for the driver diaphragms. Compared to the Grado SR325i, the Sennheisers sounded richer but slightly darker. JM found that their very effective seal created a resonant cavity that produced "bass that is both quite deep and a trifle indistinct." JA's new reference cans. Compared to the Audeze LCD-Xes, the HD650s had a similar overall sound, but lacked bass control, detail resolution, and ambience retrieval, said JA. (Vol.28 No.6, Vol.31 No.9, Vol.37 No.3 WWW)

T+A HA 200: $9650
This class-A headphone amplifier has analog and digital inputs, the latter processing DSD and PCM data independently, each in its own optimized pathway. There is a choice of four reconstruction filters plus a NOS (non-oversampling) mode. One of the USB inputs accepts PCM sampling rates up to 768kHz and DSD up to DSD1024. (The other is for "possible future extensions.") An optional HDMI module ($600) adds two HDMI inputs and one ARC (Audio Return Channel) HDMI output. Analog outputs are balanced on a 4.4mm Pentaconn jack, balanced on a 4-pin XLR jack, and single-ended on a standard 1/4" stereo jack. Each output has adjustable impedance. Comparing the T+A with the Pass Labs HPA-1, HR felt that the German HA 200's soundfield was "more of one piece, the music more relaxed." Comparing the T+A with the Benchmark HA4, he felt that the expensive German amp beat the moderately priced American amp "at its own force, clarity, and specificity game." (Vol.44 No.2 WWW)

Warwick Acoustics Bravura: $5995;
with "Black Edition" finish: $6795
This British electrostatic system includes a D/A-energizer/amplifier. The headphones use patented membrane technology that employs a thin laminated film affixed to an open, eight-cell insulating spacer made of Formex. HR described the Bravura's sound quality as "clearly stated, tight and strong of bass, and rhythmically forceful, with good body and timbre." He concluded that "The Bravura's unbypassable digital processing made it impossible for me to say anything verifiable about how Warwick Acoustics' newest electrostatic headphone system compares to any other electrostatic headphone you might be familiar with. But my diverse listening experiments lead me to conclude that, for anyone seeking a handsome, comfortable, reasonably priced, substantially built, exceptional-sounding entry into the realm of electrostatic headphones, the Bravura is a must audition." (Vol.45 No.7 WWW)

Woo Audio 3ES: $8999 (standard version)
Two-chassis, 53lb headphone amplifier with XLR and RCA inputs but only balanced outputs, which doubles as a preamplifier. Standard-version tube lineup is four Psvane 300B directly heated triodes, two Russian-made 6SN7 dual triodes, and a single (Russian) 5U4G rectifier tube. Elite edition ($11,699, not reviewed) offers upgraded components. As a preamplifier, compared with HR's reference Rogue RP-7 the 3ES was "more spirited, more physical, more locomotive-rolling-forward." As a headphone amplifier—it can drive both dynamic and electrostatic headphones—HR found that with Audeze CRBNs the Woo produced sounds that "were exquisitely formed, distinctly visual, and exceptionally three-dimensional." With the Stax SR-X9000 electrostatics, the 3ES emphasized the speed and timing of the groove, though it sounded cooler and dryer than the Linear Tube Audio Z10e, with less detail. (Vol.45 Nos.1 & 3 WWW)

B

AudioQuest DragonFly Red: $249.95 $$$ ★
AudioQuest DragonFly Black: $129.95 $$$ ★
AudioQuest DragonFly Cobalt: $349.95
In 2016, AudioQuest replaced their original DragonFly USB D/A processor-headphone amplifier with two new models—the DragonFly Black and DragonFly Red. Like their popular forebear, both models were designed by computer-audio pioneer Gordon Rankin, and both offer 24 bit/96kHz resolution. AD wrote of preferring the DragonFly Black's "superior musical incisiveness" compared to the original 'Fly of 2012; for its part, the Red, which has higher output voltage than the Black, offered "surer reproduction of pitches and timing." But he felt that, for headphone listening with an iPhone, there's no sense opting for the twice-as-expensive Red if that's all the consumer has in mind. The new (2019) DragonFly Cobalt boasts a faster microcontroller and a newer processor chip (the ESS ES9038Q2M), plus improved power-supply filtering. When used in his home system, the Cobalt impressed JA with better bass extension and control than the Red, which also sounded "slightly 'harder' in the highs"—although he also noted that the distinctions between the two tiny DACs were "relatively small." JA the Measurer, who in 2016 noted that neither the Red nor the Black were at the head of the class in terms of jitter rejection, observed "excellent rejection of word-clock jitter" from the Cobalt, which he praised for "[performing] well on the test bench." JA adds some remarkable praise for a $300 DAC: except for its limited ability to drive low impedances, the Cobalt would be Class A. (Vol.39 No.9, Vol.42 No.12 WWW)

Questyle Audio M12: $139
This tiny, 2"-long USB D/A headphone amplifier has a USB-C port on one end and a 3.5mm stereo headphone jack on the other. The Questyle can decode 16-, 24-, and 32-bit PCM data sampled at all rates from 44.1 to 384kHz, and DSD data up to DSD256, and can act as an MQA renderer. Barely visible LEDs indicate the incoming data format and whether the M12 is operating with high or low gain. (It automatically detects the impedance of the headphones plugged into it and adjusts the gain accordingly.) JA felt the low frequencies were too warm with the 23 ohm AudioQuest NightHawk headphones, but the bass was better-defined both with low-impedance Audeze LCDXes and high-impedance Sennheiser HD-650s. The M12's clarity with all three headphones was impressive. In level-matched comparisons with the more expensive AudioQuest DragonFly Cobalt, the instrumental images sounded a touch more palpable with the pricier dongle. However, the M12's "transparency, coupled with the ability to control the low frequencies with low-impedance headphones, is impressive for such a relatively low-priced device," JA concluded. (Vol.45 No.2 WWW)

C

Apple AirPod Pro 2: $249/pair
Although the new Bluetooth 5.3 standard implemented in the Pro 2 can handle lossless streaming, Apple sticks to its own AAC codec for this noise-canceling wireless in-ear monitor. RvB commented that in terms of convenience and thoughtful touches, the AirPod Pro 2 made the ownership experience second to none—"awe-inspiring, in fact." An interactive ear test lets you tailor the Pro 2's sound to your ears and compensate for hearing deficiencies. Additionally, you can engage Personalized Spatial Audio after using your iPhone's TrueDepth camera to measure your face and each ear, yielding a unique earprint. Although the full noise-canceling mode is best for use in noisy surroundings, RVB preferred the Transparency mode, which lets in a small portion of the room's environmental sound. "Overall, I found the music a bit more spacious with Transparency turned on, " he wrote. He concluded that while he had mixed feeling about the spatial audio surround-sound performance—it worked well with Atmos-encoded movie soundtracks but he found it mildly annoying with some music—he admired the AirPod Pro 2 for how well-thought-out it was, and loved how cleverly the pair was integrated with Apple iOS devices. (Vol.46 No.3 WWW)

Hagerman Audio Labs Tuba: $789
The Tuba, like the ZMF Pendant, uses a transformer-coupled EL84 output tube but wired in triode mode to deliver 350mW into 32 ohms, which should be enough power to drive most headphones. "It played most headphones really well," decided HR, "but its limited gain and low power prevented it from being considered as an all-purpose giant killer." Compared to the Pendant or the Feliks Euforia, the Tuba had a clear but "short" sound, wrote HR. With Grado GS3000e open-back headphones, the Tuba generated a tidy, naturally detailed, highly musical sound that HR found 100% enjoyable. "Midrange tone was exemplary," he found. (Vol.43 No.4 WWW)

Schiit Audio Vali 2+: $149
This bargain-priced headphone amplifier uses a single 6BQ7A/6DJ8/6922 dual-triode tube, has both RCA and headphone outputs, and has high gain and unity gain settings. HR commented that it was "impossible to not notice how much solidity, punch, drive, and bite the Vali 2+ (on Low gain) had powering the 32 ohm, high-sensitivity (106dB/mW/1kHz) Focal Stellia closed-backs." However, he did find that the more he raised the volume, the harder the sound got. Nevertheless, if a $149 headphone amplifier must veer from perfection, maybe it is best if it goes soft and colorful, as the Vali did with Focal Clear headphones. "Hard, gray, and glaring is more the norm in this price range," HR reminded us. Replacing the stock 6BQ7A tube for a NOS, made-in-Japan, Electric Industry Co. 7DJ8, the effect was "lit from the inside" luminosity with greater definition and voice intelligibility. On the test bench, the Vali 2+ offered a low level of predominantly second-harmonic distortion in unity-gain mode, but this harmonic did increase significantly in high-gain mode. As this wasn't accompanied by higher-order harmonics or intermodulation distortion, JA felt that he would expect a "fatter" sound in this mode. (Vol.44 No.5 WWW)

Deletions
Auris Audio Nirvana, Schiit Audio Jotunheim R, discontinued. HifiMan Shangri-La Jr, Meze Audio 99 Classic, Shure KSE1200SYS, not reviewed in a long time.