August 2026

North America Premiere Review!
Esoteric S-05XE Amplifier Review — A Magical Amp That Transports You Deep Into The Music
Recreating music performances with uncanny realism, emotional depth, and soul-stirring performance.
Review By Tom Lyle

  The Esoteric S-05XE Class A stereo, bridgeable power amplifier is the first Esoteric component I've reviewed for Enjoy the Music.com. Formed in 1987, Esoteric is the TEAC Corporation's "ultra-premium" high-end consumer audio equipment brand. Esoteric designs and builds amplifiers, digital converters, and disc transports. They are all handcrafted in Tokyo, Japan.

Class A
The Esoteric S-05XE is a power amplifier rated at 30 Watts per channel into 8 Ohms. Its most noteworthy feature is its Class A circuit design. For those not familiar with solid-state Class A power amplifiers, the main difference between them and more conventional Class AB or D amps is that a Class A amplifier's transistors are biased to always remain fully "on". In most other amplifier types, they turn on and off in response to the musical signal. Class A power amps offer sonic benefits because their transistors operate continuously. This eliminates crossover distortion and helps reproduce sound without the harsh frequency peaks, unnatural edginess, or listening fatigue sometimes associated with more customary Class AB or Class D amplifiers. But as some say, there is no such thing as a free lunch. Because fully active Class A devices are always in the "on" state, these power amps operate at only 20% to 25% efficiency. As a result, they typically run very hot because unused energy is dissipated as heat.

Since Class A amplifiers draw so much continuous current, they often require larger power supplies. This may be one of the reasons why its cabinet is so larger than I would have thought for an amplifier that has an output of 30 Wpc into two channels. Even so, its cabinet is not that large; measuring 17.5" x 8.75" x 21" (WxHxD) and weighing 56 pounds.

The Esoteric S-05XE power amplifier's cabinet, available in black or silver, includes Esoteric's patented isolation feet and a "semi-flowing" top plate. Together, the cabinet's feet and top plate help reduce vibration, which can cause noise and distortion. These can also reduce mechanical stress, which can reduce the transparency and affect the amplifier's soundstage.

Notable
The S-05XE amplifier has two notable features that are accessible on its rear panel. Firstly, the Esoteric S-05XE Class A amplifier can be bridged to mono by the flick of its Triple Drive Mode switch. Selecting the BTL option (Bridge-Tied Load), this changes the stereo amp to a monoblock with an output of 120 Watts. If I had known this, I would have asked them to send me a pair of monoblock S-05XEs!

The other switch worth mentioning is labeled "Auto Power Save", which causes the power to shut off if the amp doesn't receive a signal for 30 minutes. This is a Class A amplifier, so even at idle it draws almost 200 watts. So, I found this control very useful. There are many times when I fail to manually switch a solid-state amplifier to "off" after a listening session. Problem solved.

Time
On its website, Esoteric says that it spent considerable time during the S-05XE's research and development phase. Much of this work aimed to address Class A's drawbacks while retaining its benefits. One of their greatest challenges was dealing with the heat that Class A amps release. In the past, I've had some Class A solid-state power amplifiers get so hot I couldn't even touch their top plates. They could have doubled as space heaters. Esoteric has almost eliminated this heat in the S-05XE, thereby protecting the internal circuitry and other components.

High-Grade
Esoteric's S-05XE handles current with a 1,000 VA toroidal-core transformer and high-grade 10,000 μF custom capacitors for each channel. These capacitors are "Grandioso-grade," meaning they are very similar to those used in the company's top-of-the-line Grandioso components.

Esoteric also claims to use a transformer with a current-supply capacity that exceeds the amp's specifications, thereby improving responsiveness to sudden changes in current demand. The result is greater dynamic responsiveness and a more open, realistic sound. Plus, the transformer has no enclosure, which reduces the effects of vibrations at loud listening levels and other factors.

Its newly developed 1,000 VA toroidal-core power transformer stands out for its low leakage flux, which delivers an exceptionally high transient response. Low leakage flux means less magnetic field escapes from the transformer. When leakage is low, the primary core couples more fully with the secondary winding. In addition to improving the amplifier's transient response, this increases efficiency and helps prevent unwanted electromagnetic interference (EMI).

An additional feature of the S-05XE is its fully dual-mono construction and power-supply smoothing circuits, which enhance channel separation.

Balanced
The amp also uses what they call a Fully Symmetrical Balanced Input Buffer Amplifier. This dedicated front-end circuit isolates upstream components such as a preamp from the amp's output stage. It converts incoming signals using matched positive- and negative-circuit pairs, reducing EMI and other noise for a more detailed, transparent sound.

Many amplifiers and other components have a balanced (XLR) input on their rear panel and convert the signal to an unbalanced format with a simple internal adapter. Not the S-05XE. Its signal remains fully balanced, so when one uses a balanced interconnect between the preamp and the amp, as I did, the amp takes advantage of this balanced connection, reducing noise and providing other improvements in sound quality such as greater transparency, dynamics, and musicality.

Auditioning
Rather than auditioning the Esoteric S-05XE power amplifier in my dedicated listening room, where my main system resides, I listened to it in my second system in the living room/dining room area of our home. My main system uses the rather large, relatively low-sensitivity Raidho TD 4.2 loudspeakers, and imho the 30 Wpc Esoteric S-05XE may not be able to drive them properly. I've learned my preferences to drive them means they need at least 250 Wpc. (Editor's Note: I always suggest trying an amplifier within your sound system / room, as there are variables and personal preferences.)

My main system is in a dedicated, acoustically treated listening room. The second system in which I auditioned the Esoteric S-05XE power amp is a more live-sounding room, but the furniture and window shades provide enough absorption that I can hear the contributions of this Class A 30 Wpc amplifier without too much influence from the room's sound.

So, I set up the S-05EX stereo Class A amplifier on an amp stand in front of the second system's equipment rack. I listened mostly to digital sources, using either my iPad with its Tidal and Hi-Res Music lossless Qobuz streaming service apps, powered by the giant-killer FiiO S15 Music Streamer, or occasionally playing the music through the excellent-sounding aptX Bluetooth receiver in the Audio Analogue aaDAC. I also occasionally used the now discontinued but very good OPPO BDP-83E universal disc player to play the occasional physical CD or SACD.

And I did listen to some vinyl LPs on my turntable through the Esoteric S-05XE with excellent results. In this system, I used the surprisingly good Pro-Ject X2 turntable, which earned Enjoy the Music.com's Best Of 2020 Blue Note Equipment award. I used an Ortofon MC WindfeldTi phono cartridge mounted on its integral tonearm, which is connected to a Pass Laboratories XP-17 phono stage preamplifier.

All this front-end equipment was connected to a Pass Labs two-chassis XP-22 preamplifier, which in turn was connected to the Esoteric S-05XE via Kimber Carbon 8 XLR interconnects. I purposely used a balanced cable because of the previously mentioned S-05XE amp's newly designed, fully symmetrical balanced input buffer. All the gear's AC power cords were connected to a Panamax M5510-Pro power conditioner.

I used three different loudspeaker stereo sound systems when listening to the Esoteric S-05XE. The bulk of my audition was with the Vermouth Monitors, which feature a D'Appolito array, followed by the EgglestonWorks Isabel Signature two-way floorstanding speakers and a pair of vintage Magnepan SMGb planar-magnetic loudspeakers.

Impressed
I was extremely impressed with the sound quality that the Esoteric S-05XE contributed to my system. The S-05XE's transparency was one of its greatest virtues. But it also had an extremely musical sound that made the music come alive in my room.

I have read about or overheard some audiophiles boast that their systems are time machines, bringing recordings to life and recreating events that occurred ages ago. Or I might have even written that in one of my reviews! For a system to do this, everything in the audio chain, from the front end to its speakers and everything in between, must contribute. Before the Esoteric S-05XE became part of the review system, I'm not so sure that I'd make that claim. The Esoteric S-05XE stereo amplifier was the epitome of musicality, and with a decent recording, the system now, in a way, had the ability to time travel.

Fire
One of the first albums that truly impressed me when played through the Esoteric S-05XE amplifier was Queen's Live On Fire At The Bowl. I listened to it via both Qobuz and its three-LP vinyl set. Curiously, the version on Qobuz is CD-quality, but the vinyl was mastered from 24-bit/96kHz files. Go figure. This album was recorded in 1982 but released in 2004. It is the soundtrack of the concert at England's Milton Keynes Bowl in June 1982. The DVD of this concert uses a 5.1 mix, but long live legacy two-channel audio!

Even though I listened to this album at a healthy volume, this system obviously couldn't match the concert's actual volume. Still, regardless of which set of loudspeakers I was using, the Esoteric S-05XE created a huge soundstage that enveloped me and both loudspeakers, giving me the impression of the immersive, large space where it was recorded – the Milton Keynes Bowl – which seats about 65,000 people.

Each of the three types of loudspeakers I used during the Esoteric S-05XE's audition period had its own sonic characteristics, yet all reproduced the Esoteric amp's sonic personality, or more accurately, its mega-transparency. One of the Esoteric S-05XE's sonic characteristics is that its sound resembles what comes through its inputs more than having a sound of its own. It has a "Goldilocks" sound.

Has anyone gone to see an un-mic'ed jazz ensemble and remarked, "Wow, the band's imaging is fantastic!" I doubt it. The S-05XE is neither overly detailed nor lacking in detail. Its imaging is extraordinary, but it doesn't throw up unrealistically pinpoint images. Instead, it's "just right." It delivers a portrayal of the recording itself and relies on the source and upstream equipment to produce a miniature representation of the actual event, with an amazing level of separation between voices and instruments.

Vocalist Freddy Mercury's voice was front and center, but larger than life (as Mercury was in the real world), perfectly centered between the two loudspeakers. It sounded like a human being singing into a high-quality microphone. Guitarist Brian May, one of the best rock guitarists on planet Earth, has his signature guitar sound panned a bit more toward one speaker. If he had been recorded any louder, it would have torn my speakers apart. Roger Taylor's drums were realistically scaled across the soundstage, starting well behind the front wall and creating an aura of sound around and between the stereo loudspeakers.

In the case of this Queen live recording, again, what I heard was more about the sound quality of the recording and upstream equipment than this amp, which was thankfully quite good. What the audience heard that evening was probably excellent, but what I heard during my listening sessions made me feel as if I had the best seat in the house.

Surprised
When I have guests in my listening room, many are surprised to see how many classical music LPs I have. Most are original pressings, but there are a host of relatively recent reissues from various popular "audiophile" labels, including Speakers Corner, Analog Productions, and Classic Records. But I was surprised when I managed to acquire a superb 180-gram all-analog pressing on Sony Classics, a reissue of an early stereo recording of Stravinsky's Le Sacre Du Printemps (The Rite of Spring), with Leonard Bernstein conducting the New York Philharmonic.

The original LP was released in 1958 on a Columbia "6-eye" stereo LP. This 2013 release surpasses the sound quality of the original and especially its later re-pressings by quite a bit. This "audiophile" pressing is completely remastered from the original tapes. Its most substantial improvement is that it removes the original's added compression, which made the tranquil sections of this masterpiece sound nearly as loud as its more clamorous passages.

This reissue reveals that the original tape of this performance is fabulous, as is typical of many early stereo recordings that record labels deemed very important back then. And so most were made with the utmost precision. I like to say they did this with an exactitude almost equal to that used by NASA when it first launched humans into suborbital space in the early 1960s. Besides its superb sound quality, I believe this is one of the best recorded performances of The Rite of Spring I have ever heard. "Breathless," "swaggering," and "visceral" are words that many critics used to describe this reading.

Regardless of which stereo system or amplifiers I've used to play this vinyl LP, this reissue shines through for many reasons, including making formally buried sounds now clearly audible, its crystal-clear transparency and rendering of a near-perfect string sound and explosive percussion.

Through my main system, the lower frequencies are more seismic. Yet the system used for this review is nothing to scoff at. It took me only a few minutes to realize this when I first heard this album through the system that included the Esoteric S-05XE Class A power amplifier.

In the introduction to the first section of The Rite of Spring, titled "The Adoration Of The Earth", a bassoon solo is written in the instrument's rarely used higher registers, representing springtime. On some recordings, it's tough to discern the instrument. Still, there is no doubt here, as the bassoon's expressive, reedy sound was perfectly reproduced by the S-05XE, displaying its very transparent, lovely-sounding upper-midrange.

It was during the second half of this score, titled "The Sacrifice," that I turned the preamp volume louder than its already high level. Despite the brilliant pandemonium from my speakers, I heard zero distortion through the Esoteric S-05XE, even during the piece's most climactic scenes. At this formidable volume, the orchestra played with strings and winds madly in variable time signatures, overlaid by a battery of percussion.

It was during the second half of this score, titled "The Sacrifice," that I turned the preamp volume louder than its already high level. Despite the brilliant pandemonium coming from the speakers, with the orchestra's strings and winds madly playing in variable time signatures while overlaid by a battery of percussion, I heard zero distortion through the Esoteric S-05XE, even during these climactic scenes.

But the sound quality of the Esoteric S-05XE offered more than I could describe using my admittedly often-overused audiophile vocabulary. What I heard from it was a very musical sound, letting me hear more than I already described. What this amp did was convey the music's meaning, its indescribable emotional backing.

This made me involuntarily picture Bernstein's enthusiasm on the podium, along with images of the dancers on stage from the reimagining of the original ballet when I saw it nearly 25 years ago. I've heard this masterful score countless times, yet I still feel an emotional connection to it. This only happens to me when I hear music or when I'm listening through the very best high-end audio equipment. Which, of course, includes this Esoteric Class A power amp.

Again
When it came time to write this conclusion, the price of the Esoteric S-05XE Class A power amplifier slipped my mind. So, I was facing the dilemma of recommending a high-end audio component with a price that would be out of reach for many audiophiles.

The Esoteric S-05XE costs $13,500, which I realize isn't chump change. But when auditioning this power amplifier, I assumed it cost at least twice as much as its list price. No, I still wouldn't dare call it a "bargain." Especially since it's "only" a 30 Watt per channel power amplifier. But if one has, or plans to have, a pair of sensitive speakers and its price is within one's reach, I'd have no reservations recommending the Esoteric S-05XE Class A power amplifier.

Distributor Comments
We want to extend our thanks to Tom Lyle and Enjoy The Music.com for taking time to perform a very thorough and thoughtful review of the Esoteric S-05XE. The review has captured the spirit, heart and potential of this very important product. We would, in conjunction, like to offer a couple of supporting points to topics covered in the review.

It is important, and desirous, to have your products integrate with other brands and design philosophies. The broad selection of products used in conjunction with the S-05XE, resulting in such a positive review, demonstrates the amps achievement on this matter. At the same time, we want to highlight the function of Esoteric's proprietary ESLA signal path, which could not be addressed in the review without the presence of complimentary Esoteric components. The use of an Esoteric front end would add the recognizable sonic benefits of this technology and take the musicality, transparency and speed of the amplifier's response time to an even greater level than even that realized and noted during the review process.

We also would like to suggest that while Watts Per Channel is a commonly referenced specification, it conceivably tells only a small part of the story, in our opinion. 'Current Output' of the amplifier is more telling when it comes to being able to drive a loudspeaker. The current output of the S-05XE is exceptionally high, and while the aforementioned Raidho TD-4.2 were not used as part of the review for concerns over Watts Per Channel; loudspeaker nominal ratings consider primarily the presence of a Class A-B amplifier, not Class-A. We have ourselves used this excellent product from Raidho in presentations of our own without issue and we do not believe there should any reservation by a potential consumer about the S-05XE's ability to drive the great majority of loudspeakers available on today's market.

Thank you.

Keith Haas
Director of Sales - HiFi
Playback Distribution

Specifications
Type: Solid-state Class A amplifier, bridgeable to mono
Rated Output Power: 30 Watts per channel, two channels @ 8 Ohms in Class A.
    60 Wpc @ 4 Ohms and 120W (BTL Mode @ 8 Ohm)
Frequency Response: 5Hz to 100kHz (+0dB/–3dB @ 8 Ohm)
Signal To Noise (S/N) Ratio: 104dB (IHF-A, XLR)
Distortion: 0.007% (1kHz, 8 Ohm, 30W)
Compatible Speaker Impedance: 4 to 16 Ohm, 8 to 16 Ohm (BTL Mode)
Gain: 28.5dB, 34.5dB (BTL Mode)
Damping Factor: 500
Analog Audio Inputs: ES-Link Analog: RCA 1 Pair, XLR: 1 Pair
Input Impedance: 10kOhm

External Control 
Trigger In: 1 (3.5mm Mono Mini Jack)
Input Level: 12V, 125mA
Trigger Through: 1 (3.5mm Mono Mini Jack)

General
Power Supply: AC 230V 50Hz (Europe), AC 120V 60Hz (US/Canada)
Dimensions: 17.5" x 8.75" x 21" (WxHxD) 
Weight: 56.4 lbs.
Price: $13,500

Manufacturer
Esoteric International
1-47 Ochiai, Tama-shi
Tokyo,206-8530 Japan

Voice: +81 42-356-9235
Website: Esoteric.jp

U.S. Distributor
Playback Distribution LLC.
3257 Wildlife Trail
Zionsville, Indiana 46077

Voice: (844) 472-3478
Email: info@playbackdistribution.com 
Website: PlaybackDistribution.com