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Before embarking on this review, I hadn’t heard much about JE Audio, a company based in Hong Kong. But when editor Jeff Fritz asked if I’d be interested in reviewing JE’s Dyad S400 amplifier ($16,000 USD), I thought it might be an opportunity to discover an overlooked gem. I was soon in touch with John Lam, JE’s founder and chief designer, and not long after that, a review sample was on its way from Asia to Illinois.


JE Audio Dyad S400In just a few days, the Dyad S400 arrived at my doorstep in a flight case -- a pleasant surprise, as it made handling the amp a whole lot easier for me and the DHL deliveryman. Previously, I’ve seen flight cases from only a few European companies. I wrestled the case into my listening room, opened it, and there, in a black velvet sack, under the owner’s manual and a pair of white gloves, was the 95-pound S400. The flight case made unpacking and setup very simple.

The S400 is a hybrid amplifier whose driver stage includes six signal tubes -- two 12AU7s and one 6922 per channel -- and puts out 200Wpc into 8 ohms (or 400Wpc into 4 ohms). It measures 18.3”W x 8.6”H x 22.5”D and looks handsome, with a fairly minimalist design -- there aren’t a lot of buttons or fancy chassis touches. Finned heatsinks run the length and height of both side panels; although the fins aren’t sharp, neither are they rounded off, and the S400 has no handles -- so handle with care. The faceplate is silver (black is an option), thin at the top but tapering to 15mm thick at the bottom; its front profile also slightly narrows toward the top. At the top center of the faceplate is the JE Audio logo, embossed in black, and at bottom center is an On/Off switch; between them are three LEDs.

The rear panel of the S400 is fairly straightforward: an IEC connector, a rocker power switch, one set each of balanced and single-ended inputs, and two pairs of speaker binding posts. The input and output connectors are all made by Neutrik, the IEC connector by Schurter.

Inside, the Dyad S400 has a clean layout, with construction and parts qualities of the first order. All signal amplification is handled by the tubes. The current amplification is done by an all-solid-state MOSFET High Current Buffer Amplifier (HCBA) output stage with 20 power transistors per channel. Per John Lam:

The Dyad S400 is based upon the patented Dual Balanced Feedback Topology (DBFT) that makes a true fully balanced hybrid power amplifier design possible. Since DBFT allows two pairs of feedback [loops] to be used, each feedback pair only carries small amounts of feedback and hence, the overall stability can be easily controlled. By using two pairs of feedback [loops], the overall performance of the power amplifier can be easily optimized without jeopardizing the stability.

When the main power switch on the S400’s rear panel is thrown, the middle LED turns amber, to let you know that the amp is receiving power. To ready the S400 for playing music, you push the On/Off button and hold it for three seconds. The S400 then emits a click, and the three LEDs turn blue and begin to flash, two at a time. This continues for about 40 seconds, as the amp completes its soft-start procedure. During this time, the power inrush current is reduced, the tubes are warmed up, and the protection circuits check that everything is working correctly. That done, the flashing stops, the center LED stops flashing and glows a steady blue, and you’re good to play music.

My system

My analog front end comprises a Merrill Heirloom turntable, Jeff Rowland Design Group Consonance tonearm, Transfiguration Phoenix cartridge, and an ASR Mini Basis phono preamp. The digital front end is an Asus laptop running JRiver Media Center 17 sending music files, via an excellent Clarity Cable USB cable, to an Abbingdon Music Research DP-777 D/A converter. The Abbingdon’s excellent analog output section drives my Purity Audio Silver Statement preamplifier. A major improvement in my system’s sound has been the addition of MSB’s M202 class-A mono amps. I still use my McAlister OTL-195 mono amps when I want the flavor of tubes, but the MSBs are something special. I use Silnote interconnects between the DP-777 and the Silver Statement and between the Silver Statement and the McAlisters, and with the phono preamp. The rest of the cables and power conditioning are all by Sound Design Labs: TC8 speaker cables, power conditioner, and accompanying BD3-SE power cord. Though I still use my Meadowlark Heron dynamic-driver speakers, my reference speakers are now the King electrostatics from KingSound, another Hong Kong company, driven by custom power supplies designed and built by Don Smith at Sound Design Labs.

The Dyad S400 was an excellent performer in my system. No pops or sounds ever emanated from it that drew my attention or gave me reason for pause. I was a little nervous any time I needed to push the On/Off switch and hold it for the requisite three seconds, but this caused no problems. When I review a component, I do a lot of cable swapping and moving of equipment in and out of the system. As I don’t want to blow anything up, I’m always very careful to turn everything off beforehand.

I gave the S400 a thorough workout in the time I had it, and it was always well behaved. It never got hot, even when driving the KingSound electrostats. On many occasions I did prolonged, heavy-duty listening at high volume levels of +95dB, but the JE Audio never got more than lukewarm to the touch.


JE Audio Dyad S400After getting familiar with the S400 and setting it up in my system, I settled down to do some listening. I was more than a little surprised, and pleasantly. The S400 took complete control of my KingSound electrostats, wringing from them a lifelike realism similar to what tube amps can do, but with an ease and abundance of drive that tubes usually can’t provide.

I’ve heard solid-state amplifiers, such as Simaudio’s powerful Moon Evolution W8, drive the Kings with tremendous ease and deep bass, but have always wished for a little more refinement in one area or another. Tube amps would give me most of what I wanted, but not the W8’s drive and authority. The 195W of output-transformerless (OTL) tube life that the McAlisters provide is pretty close to being entirely satisfying, but the S400 improved the bass a little bit.

The S400’s sound was slightly to the warm side of neutral, and nowhere close to etched or bright. At the same time, it provided large amounts of detail and generous information about the recorded event. Spatial cues were easy to note -- my speakers threw a wide, deep, airy soundstage. The sound was breathtaking in the way it layered information -- I was able to hear the space around performers on the stage. Transients were realistic and natural, at no time sounding emphasized or standing out from the rest of the music. Drumsticks and brushes sounded realistic when struck. Rim shots had an “in-the-room” quality. The bass was fully extended, and also seemed to be fully detailed -- I could feel and hear the bass notes filling the room, even as I could hear the details of the notes’ decays. I could feel the bass in my chest when the music called for it, but with jazz and classical recordings the bass was very refined. High frequencies were sweet, detailed, and extended. The sounds of instruments such as bells and triangles were natural, and lingered ever so slightly before tailing off.

The greatest strength of the Dyad S400 was its midrange performance. It rendered the high and low frequencies with heightened realism, but the midrange drew me into the music and made my experience of it palpable. Voices had an organic, expressive sound that had an almost tangible quality that increased my feeling of hearing a singer or soloist in my room, and allowed me to more easily connect with the singer or player.

JE Audio Dyad S400

Listening to Anton Bruckner’s Symphony No.4, with Herbert von Karajan conducting the Berlin Philharmonic (CD, EMI AM-34735), the S400 gave me an authentic sense of scale due to the realistic reproduction of ambience; I heard a holographic quality like that of a large concert hall. The S400’s handling of detail in the sounds of the brass and the rising power of the crescendos were worth noting for their sense of realism. I heard another example of the S400’s abilities with symphonic music with recordings by Leonardo García Alarcón conducting the New Century Baroque in works by Mozart: the Requiem (with Choeur de Chambre de Namur) and the Clarinet Concerto (with soloist Benjamin Dieltjens). This 24-bit/96kHz FLAC from the Ambronay label has a warm, airy depiction of an immense hall with an abundance of hall sounds. The S400 did an excellent job of revealing the complex colors, textures, and dynamics of this fascinating recording.

With Berlioz’s Roméo et Juliette, in a recording by Charles Dutoit and the Philadelphia Orchestra (24/88.2 FLAC, Philadelphia Orchestra), the S400 delivered a believable replication of the breadth and scope of the orchestra, whose different sections were well delineated and easy to follow. The S400 did a good job of letting me hear the layering of the string section, and had very wide dynamic range, with a warm, natural-sounding bass that had excellent extension down low.

One of my new favorite recordings is Jean-Pierre Mas’s (H)ombre (16/44.1 FLAC, Sunnyside), which I enjoy for the different melodies, the interesting percussion, and the deep, powerful bass in several tracks. The S400 reproduced the midbass punch and strong lower-end bass of “Poule d’Eau,” and the bird sounds at the beginning of this track sounded as if birds were in the room with me. The S400 also captured the naturalness and the rich palette of the piano in “Marianne,” and reproduced the warm midrange of the ethereal-sounding “Prélude en Mi Mineur,” with its slow moving, lush-sounding piano and percussion. With the faster tempo and Latin beat of the salsa-influenced “Flor de Venganza,” the S400 easily reproduced the changes of tempo and rhythm.

Another trusted reference that tests an amplifier’s mettle is Hugh Masekela’s Live at the Market Theatre (CD, Four Quarters Entertainment 1805). The entire two-CD set is excellent, but my favorite track is “Stimela.” Very dynamic and very detailed, it tests an amp’s ability to play loud while replicating realistic transients. The S400 passed with flying colors, even while driving a pair of KingSound electrostats to high volume levels.

An interesting disc I’ve been listening to lately comes from a local -- Chicago trumpeter Corey Wilkes. On Drop It (CD, Delmark DE582), he plays up-tempo, funky jazz. Tracks like “Ubiquitous Budafly” and “Searchin’” bring to mind one of my favorite trumpeters, the late Lester Bowie, and the S400 did an admirable job of capturing the tonal colors of Wilkes’s trumpet. What’s even more compelling on this disc, at least to me, is the first track, “Trumpet Player,” which seems to have been recorded live in a club. Singer Dee Alexander recites a poem by Langston Hughes, her voice sounding so real and lifelike that it caught the attention of everyone I played it for. The S400 did a great job of bringing the sounds of the club to life -- it was easy to believe that Alexander was reciting the poem in my room.


I made several lively equipment comparisons while the S400 was in my listening room, a period during which I was also looking for a reference solid-state amp to go along with my McAlisters. I had an enjoyable time comparing the S400 ($16,000) with Simaudio’s Moon Evolution W8 ($10,500, discontinued). In terms of build quality, and low-end control and extension, you couldn’t want more than what the W8 provides -- its bass performance and power output are prodigious. However, the Dyad S400 performed slightly better in the midrange, which made everything ever so slightly more present and realistic. The S400’s upper frequencies were slightly more extended, and the JE was clearly better at rending acoustic stage properties.

Another close comparison was with my McAlister OTL-195 mono amps ($8500/pair). The McAlisters’ very fast, lifelike sound is well extended at the frequency extremes, and seemingly powerful enough to drive the KingSound electrostats like no other tube amp I’ve used. Though they look nice and sound wonderful, they’re not well made -- which is why I was looking for a reference solid-state amplifier. The McAlisters had a slight edge on the S400 in the midrange -- there’s some magic in their OTL sound. That said, the S400 did a better overall job, with a more focused sound, and a low end that spoke with more power and authority than that of the McAlisters. The higher-frequency performances of both amps were close enough that I found it difficult to say that one was better than the other. But at the end of the day, I’d choose the JE Audio over the McAlisters for the former’s build quality and sound at the extremes of the audioband.

The only amps I had on hand that I felt outperformed the Dyad S400 -- and, again, it was close -- were MSB’s M202 mono amps ($17,500/pair). The JE and MSBs sounded comparable in the midrange and came out very close. The M202s were slightly more lifelike in the highs, though the S400 didn’t at all lack in this area. The M202s spoke with a more authoritative low end, and had a slightly easier time driving the Kings -- though I could hear this only in direct comparison with the JE Audio. When I had the Dyad S400 driving my Meadowlark Herons, or a review pair of Daedalus Argos, I heard no hardness as it drove these speakers well up to 110dB.


JE Audio’s Dyad S400 showed itself to be an excellent performer in all respects. I put it through its paces and compared it to some excellent-sounding amplifiers, and it more than held its own. The Dyad S400’s build quality and sound, even when driving speakers that are difficult loads, make it a top-flight performer in its price range that deserves to be heard by a wide audience. I highly recommend that you listen to the JE Audio Dyad S400 before buying anything close to its price.

. . . Michael Wright

Associated Equipment

  • Speakers -- KingSound King, with custom power supplies designed and built by Don Smith at Sound Design Labs
  • Sources -- Asus laptop running JRiver Media Center 17, Abbingdon Music Research DP-777 DAC; Merrill Heirloom turntable, Jeff Rowland Design Group Consonance tonearm, Transfiguration Phoenix cartridge; ASR Mini Basis phono stage
  • Preamplifier -- Purity Audio Design Silver Statement
  • Amplifiers -- McAlister Audio OTL-195 monoblocks, MSB M202 monoblocks
  • Interconnects -- Silnote
  • Speaker cables -- Sound Design Labs TC8
  • Power cables -- Sound Design Labs BD3-SE
  • Power conditioner -- Sound Design Labs
  • Accessories -- Epiphany Stand Systems Celeste Reference equipment stand

JE Audio Dyad S400 Stereo Amplifier
Price: $16,000 USD.
Warranty: Three years parts and labor.

JE Audio

Unit L, 5/F, Block 1
International Industrial Center
2-8 Kwei Tei Street
Fotan, Shatin
Hong Kong
Phone: (852) 3543-0973
Fax: (852) 3543-0971