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Haiku Audio

Manufacturer: HAIKU-AUDIO
Price (when reviewed): 29 900 PLN

Contact: Wiktor Krzak
ul. Chodkiewicza 5
31-532 Kraków ⸜ POLSKA



Provided for test by: HAIKU-AUDIO


images „High Fidelity”

No 225

February 1, 2023


HAIKU-AUDIO is a Polish company from Krakow, founded in 2012 by WIKTOR KRZAK, a musician and audio enthusiast. It took its name from the type of output gain circuit developed by Talcomp and specializes in the production of audio amplifiers. We are testing its new integrated amplifier, the SELENE, featuring KT150 tubes.

ELENE KT150 IS THE LATEST VERSION of this amplifier, designed for KT150, tubes developed and manufactured by Tung-Sol. This is a problem for manufacturers, because it is a Russian product. However, some things cannot be changed overnight, and we have to accept them as they are.

The predecessor of this model was Selene 6550, featuring obviously 6550 tubes. The new version features larger, redesigned transformers and revised components. The design of the device has also been changed, because in the middle of the front panel now there are two so-called VU-meters, measuring the voltage of the input signal. This is a big change for Wiktor Krzak, but a logical one. Until now, the "window" where the meters are located was empty.

The new tubes resulted in a significant increase in output power - instead of 30 we now get 75 watts per channel. Other measurable parameters have also changed. For example, the frequency response extends twice as high as before (!). So we can probably say that this is simply a completely new amplifier, with only some ideas taken from the previous one, the name, layout general idea and - to some extent - appearance. Therefore, a completely different one hence a higher price should not come as a surprise.

Selene KT150

In company’s materials it reads:

SELENE KT150 is an excellent proposition for sophisticated music lovers, fans of powerful, stage or symphonic music, but delivered in a natural way. Thanks to the unique design and high output, the amplifier allows you to drive low-efficiency speaker sets or fill large listening areas with natural sound. The output reaches 75W in class A. Selene KT150 amplifier has been designed for lovers of beautiful sounds - uncompromising seekers of sophisticated emotions. The device offers four line inputs. The amplifier is equipped with VU meters and a remote volume control., accessed: 29.11.2022

Selene KT150 is a tube integrated amplifier. The entire circuit works in class A, except that the preamplifier stage operates in a single-ended (SE) mode, and the output tubes work in push-pull (PP). SE means that the entire signal is amplified by a single amplifying element. In turn, PP, that the signal is divided into two halves, each of which is amplified by a separate amplifying element. The advantage of single-ended circuits is their simplicity and linear operation without problems with the zero crossing, in the vicinity of which both transistors and tubes behave less than optimal. In turn, the advantage of push-pull circuit is high output.

There are three 6SN7 tubes in the input stage of the tested amplifier, both in the preamplifier section, as well as in the phase inverter and power tube driver section. Invented in 1941 by RCA and Sylvania, they offer medium gain and feature an octal (large) base. There are two triodes in one glass bulb. The version used by Haiku Audio is special. These are high-class Psvane tubes with an unusual bulb, gold-plated pins and a high-class base. The output tubes, KT150 beaming tetrodes, were manufactured by Tung-Sol and are one of the newest tubes available on the market.

The device offers four line inputs. Unusually, the right channel inputs are placed above and the left channel inputs below; the latter is marked in green. The output sockets are convenient to use, gold-plated, single, for a loading of 6 Ω. Input selection and the volume level are controlled by large, aluminum knobs. We can also change the volume using the remote control. It is simple and easy to use.

The power supply was built using semiconductors. A filter with a choke was used to suppress power grid ripples. According to the manufacturer, advanced output transformers feature windings incorporated in anodes, shielding grids and cathodes of power tubes using the load sharing technique. All transformers were made by the Polish company Ogonowski, which supplies most of the Polish manufacturers. They were placed at the back, behind the tubes, and shielded. It looks very cool.

The signal path, from the input sockets to the output stage is built using the spatial assembly technique, using auxiliary supports. The volume potentiometer is a motorized blue ALPS, all resistors are metallized, ceramic sockets use gold-plated contacts, and - as the manufacturer says - "in the key places of the path" Nichicon Gold capacitors were used. The chassis is made of steel, painted black, and the front is made of brushed aluminum anodized black.

Haiku Audio has accustomed us to the fact that its products are very well, solidly made, nicely finished and have their own unique design. And so is the case here.


⸜ HOW WE LISTENED The Haiku Audio Selene KT150 amplifier was tested in the HIGH FIDELITY reference system and was compared to a two-box system consisting of the Ayon Audio Spheris III tube preamplifier (approx. PLN 150,000) and the Solution 710 transistor power amplifier (approx. PLN 160,000, an obsolete model); I devoted a separate listening session to comparing it with the Audio Reveal First Mk II tube amplifier.

The device was placed on the Finite Elemente Pagode Edition Mk II audio rack. It was connected with Ayon Audio CD-35 HF SACD player using RCA Crystal Cable Absolute Dream interconnects, and drove Harbeth M40.1 loudspeakers via NOS Western Electric cables. Power was provided by the Harmonix X-DC350M2R Improved-Version cable.

⸜ Recordings used in the test | a selection

Notting Hill (Music from the Motion), soundtrack, Island Records 546 428-2, Test Press CD (1999).
⸜ TOMASZ PAUSZEK, 20 Years Live, Audio Anatomy, 2 x Master CD-R (2019).
⸜ ANJA GARBAREK, Briefly Shaking, EMI 8608022, Copy Control Disc (2005).
⸜ NAT „KING” COLE z płyty Welcome to the Club, Columbia/Audio Fidelity AFZ 153, Limited Edition № 1294, SACD/CD (1959/2013).
⸜ DONALD FAGEN, The Nightfly, Warner Bros. Records/Warner Records (Japan) WPCR-14170, seria „Warner Premium Sound”, SACD/CD (1982/2011).
⸜ BRIAN ENO, The Ship, Warp Records/Beat Records BRC-505CE, SHM-CD (2015).
⸜ ERIC CLAPTON, Timepieces: The Best Of Eric Clapton, Polydor/Audio Fidelity AFZ 190, Limited Edition № 0115, SACD/CD (2014).
⸜ CHARLIE HADEN & KENNY BARRON, Night and The City, Verve Records 539 961-2, Compact Disc (1998).


HAIKU AUDIO AMPLIFIERS differ from most tube amplifiers available on the market. They differ in design assumptions, and choices made by designer, but most of all in sound philosophy. "Philosophy" in relation to the sound may seem like an exaggeration. However, I know from experience that it is adequate in such mature products as Selene. It is based on careful considerations and several proprietary solutions.

And this philosophy would consist in providing us, the listeners, with the least colored sound. It would seem that in audio this is a basic requirement, right? It is not. In order to achieve the desired result in a given budget, and audio products are simply products that are subject to the laws of the market, the designer must make compromises. We call them euphemistically "choices", but they are what they are.

In the case of the Selene KT150, as I hear it, it was about clearing the sound of the "tube warmth". It is almost always a distortion. If you are looking for this in the sound, if you want to "wrap yourself in it", look elsewhere. Haiku Audio goes in a different direction. It's a fast, dynamic and open sound. And at the same time resolving. The amplifier shows the differences between the recordings, points out their advantages and disadvantages. Trying to get itself out of the equation.

It is the case, among other things, because the tested device does not suffer from the so-called "overload stress syndrome", so to speak. Listening to the soundtrack from Notting Hill (Music from the Motion), it was impossible not to notice that the amplifier offered such a high output and current efficiency that driving the Harbeth M40.1 wasn't an issue. I would even say that it did it with ease and effortlessness unavailable to many transistor amplifiers of similar power.

So when I heard the bass framing the envelope of Ain't no sunshine by LIGHTHOUSE FAMILY, I knew that I wasn't going to catch it this amplifier with any failure. Yes, with the lowest, electronically generated bass from TOMASZ PAUSZEK or ANJI GARBAREK albums, one can feel a certain reserve in the sound of the amplifier. But I hear similar limitations with most amplifiers, regardless of the amplification technology.

This gives you an extraordinary listening comfort. This is because each album is unique and each disc is special. We change the recording and another world opens up to us. The Selene KT150 does not make them similar, because it can, for example, show differences in the relative volume level. Moving from Nothing Hill... to NAT "KING" COLE's album Welcome to the Club, I had no doubts that much stronger compression was used on the former, hence the average volume level was much higher there. This can be heard with any sensible amplifier, but Haiku Audio was much more faithful to the signal in this respect than other amplifiers.

In terms of timbre, this device is located exactly in the middle, between the "warm" and "cool" sound. It would be easiest to say that it is neutral, but we will not convey all the intricacies of its presentation in this statement. Neutrality in this case means opening up to sounds from the album. So we get a large volume and a very deep soundstage. With records like Welcome to the Club, which has a large swing orchestra on it, it will be a unique experience because usually these elements are compressed.

⸜ DONALD FAGEN The Nightfly

Warner Bros. Records/Warner Records (Japan) WPCR-14170
„Warner Premium Sound” series
SACD/CD ⸜ 1982/2011

The Nightfly, AN ALBUM RELEASED in 1982 by Warner Bros. Records, was the solo debut of DONALD FAGEN, previously a member of the Steely Dan band. It is also one of the first popular music albums entirely recorded on a multi-track digital tape recorder. Recording of the material took eight months and took place in three studios: Soundworks Digital Audio/Video Recording Studios (New York), Automated Sound (New York) and Village Recorders (Los Angeles).

For the first time, Fagen came into contact with digital technology while recording the album Gaucho with his former band. However, due to technical difficulties, this album was recorded in analog. It was similar with The Nightfly, because the then new 3M tape recorders required constant adjustment, which was managed by people from the manufacturer. Eventually, Fagen's team underwent training in this regard and operated the tape recorders themselves until the end of the session.

The system proposed by 3M consisted of a 32-track recording tape recorder and a 4-track mastering tape recorder. Both worked with 44.1 kHz sampling frequency and 16-bit word length (exactly the same as Mitsubishi tape recorders). However, the mix was done using an analog console. It took the musicians eight months to record and just ten days to mix.

Produced by Gary Katz, the album was recorded by Roger Nichols and mixed by Elliot Scheider. Unlike the Steely Dan albums, almost all the tracks were recorded separately, which the musicians did not like. Thanks to this, however, unusual solutions were reached, such as doubling the bass with the sound of a synthesizer. The digital drum machine Wendell II debuted on this album, with a resolution of 16 bits, connected directly to the tape recorder.

The edition that I would like to recommend to you comes from 2011 and was prepared by the Japanese branch of Warner Bros. records. It was created as part of the prestigious "Warner Premium Sound" series and brought not only remastered stereo material, but also multi-channel material remixed by Scheider - 5.1; the carrier was a hybrid SACD. Bob Ludwig is responsible for mastering.

When asked what is the point of releasing PCM 16/44.1 material on a SACD disc, I have a simple answer: because it sounds better. Converting PCM signal to DSD does not add more information. However, because the DSD signal is a much better carrier of the audio signal, we get a warmer and more saturated sound.

THE RANGE EDGES ARE strong and spread very wide in the tested device. They are not underlined, not stressed, but always present. The amplifier, however, sparingly doses the lower midrange. And this is something you need to consider when building your system, because it will be one of the key decisions. Like I said, the amplifier’s sound is not colored. So, if someone is looking for a device that is saturated, playing with a dense midrange, this is not the way to go, this is not the Haiku Audio philosophy I was talking about.

It's about striving for objective truth, even at the cost of rejecting choices that make listening more enjoyable. But not by thinning the sound, that's not the point. So I listened to DONALD FAGEN's album entitled The Nightfly with particular attention, because it is notoriously slimmed down by audio devices. From experience, however, I know that this is usually the problem of these devices, because they cannot show what the purity of sound achieved by the producer of the album, Gary Katz, is all about. With Selene, I knew what came from the 3M digital mastering system and what came from the device.

And thanks to all this, the space we get from the Haiku Audio amplifier is absolutely above average. And not only because of that. This was implicit in my earlier remarks, but now I must finally say that the dynamics of this device is outstanding. This is something that professional musicians are looking for in the sound, aware - very painfully aware - of the limitations of home systems in this respect.

The sounds of the synthesizer that open the BRIAN ENO’s The Ship, coming from behind our backs and far from the depths of the stage in front of us, was reproduced insanely well by the tested amplifier. It is very rare to hear something like this, that when the sound starts in front of us, and the decay is behind us - as was the case here - the transition is so smooth.

I had heard this feature before, especially with the Cole disc, but now this immersion in sound was all-encompassing. Which brings me back to where I started this test. The "entry" into the recording, which the Selene KT150 offers, consists not in warming up the timbre, but in providing the sound in the most resolving way, i.e. providing as much information as possible. And this is information, not sound manipulation. It really creates what is happening around us.


BRIAN ENO'S ALBUM has an incredibly deep sound. Both the bass extension and Eno's processed voice are fantastic. The Haiku Audio amplifier shows it with lightness and ease. It has deep bass that is well controlled. The sound is uncompressed and it seems as if the device has infinite power. It's an illusion, but an illusion of the kind that we believe in them, no matter what.

The presentation offered by the amplifier is not warm. It's not cold either. Transparent and neutral – these are probably the best terms that could be used in this case. The dynamics is above average, and the space is phenomenal. All of this says that the device has low compression and that it is great at retaining information about very low level signals, including phase information.

So it is not an amplifier for everyone, certainly not for those who are looking for "tube warmth". This is a device for those who want a clean, or even very clean sound without a trace of brightening. For those who are looking for emotions recorded in the recording, not "boosted" by the designer. Finally, for those for whom all other designs sound slow and indistinct. Selene does it all just exceptionally.

Technical specifications (according to the manufacturer)

6SN7 (x 3), KT150 (x 4)
Operation: Class A
Nominal output: 75 W
Frequency range:
• 15 Hz – 64 kHz (-1 dB)
• 8 Hz - 71 kHz (-3 dB)
Power consumption: 400 W
Dimensions (W x D x H): 450 x 320 x 220 cm
Weight: 25 kg


Reference system 2023

1) Loudspeakers: HARBETH M40.1 |REVIEW|
2) Line preamplifier: AYON AUDIO Spheris III Linestage |REVIEW|
3) Super Audio CD Player: AYON AUDIO CD-35 HF Edition No. 01/50 |REVIEW|
4) Stands (loudspeakers): ACOUSTIC REVIVE (custom) |ABOUT|
5) Power amplifier: SOULUTION 710
6) Loudspeaker filter: SPEC REAL-SOUND PROCESSOR RSP-AZ9EX (prototype) |REVIEW|
7) Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|


Analog interconnect SACD Player - Line preamplifier: SILTECH Triple Crown (1 m) |ABOUT|
Analog interconnect Line preamplifier - Power amplifier: ACOUSTIC REVIVE RCA-1.0 Absolute-FM (1 m) |REVIEW|
Speaker cable: SILTECH Triple Crown (2.5 m) |ABOUT|

AC Power

Power cable | Mains Power Distribution Block - SACD Player: SILTECH Triple Crown
Power (2 m) |ARTICLE|
Power cable | Mains Power Distribution Block - Line preamplifier - ACOUSTIC REVIVE
Power Reference Triple-C (2 m) |REVIEW|
Power cable | Mains Power Distribution Block - Power amplifier - ACROLINK Mexcel 7N-PC9500 |ARTICLE|
Power cable | Power Receptacle - Mains Power Distribution Block: ACROLINK Mexcel 7N-PC9500 (2 m) |ARTICLE|
Power Receptacle: Acoustic Revive RTP-4eu ULTIMATE |REVIEW|
Anti-vibration platform under Acoustic Revive RTP-4eu ULTIMATE: Asura QUALITY RECOVERY SYSTEM Level 1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RPC-1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RAS-14 Triple-C |REVIEW|
Passive filter EMI/RFI: VERICTUM Block |REVIEW|


Speaker stands: ACOUSTIC REVIVE (custom)
Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|
Anti-vibration platforms: ACOUSTIC REVIVE RAF-48H |ARTICLE|

  • HARMONIX TU-666M "BeauTone" MILLION MAESTRO 20th Anniversary Edition |REVIEW|


Phono preamplifier: Phono cartridges: Tonearm (12"): Reed 3P |REVIEW|

Clamp: PATHE WINGS Titanium PW-Ti 770 | Limited Edition

Record mats:


Headphone amplifier: AYON AUDIO HA-3 |REVIEW|

Headphones: Headphone Cables: Forza AudioWorks NOIR HYBRID HPC