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Flow by Allegro

Manufacturer: ALLEGRO AUDIO Ltd.
Price (when reviewed): €13,000

Andrássy út.20. door bell: 16
H-1061 Budapest ⸜ HUNGARY


Provided for test by: FLOW BY ALLEGRO


Images: Allegro Audio | Wojciech Pacuła

No 212

January 1, 2022


FLOW BY ALLEGRO is a Hungarian company established in 2018, specialized in manufacturing audio amplifiers. The company's founder and constructor is Mr. BÉLA TELEKI, but it is a family business – 50% belongs to his wife, Mrs. ANDREA OHÁR. We are testing its largest, most powerful and most expensive amp, FLOW ONE. This is WORLD PREMIERE.

HE TEST OF THE MOST EXPENSIVE AMPLIFIER of the Hungarian brand FLOW BY ALLEGRO had been planned for over three years. First, we postponed it for reasons not related to audio, but then because of the pandemic. Finally, we managed to reach our goal – Mrs. ANDREA OHÁR and Mr. BÉLA TELEKI, business partners and spouses in private, brought their top-of-the-range design, the integrated FLOW ONE amp, to Cracow.

The company made its debut at the international stage in 2018 at the AUDIO SHOW VIDEO SHOW PRAGUE and I liked the Flow One amp they then presented enough to be awarded our BEST SOUND award. This year, Flow by Allegro has achieved the same success, as its presentation during the Too Loud Fest in Zagreb was also liked very much.

A few simple words with…

Owner, constructor


WOJCIECH PACUŁA Tell me a few words about how the company was established.
BÉLA TELEKI I HAVE BEEN DEALING WITH AUDIO PRODUCT RETAIL SALES already since 1998 (all text effects have been added by the Editor). My first company, set up in cooperation with a colleague, was originally named Agria Audio. However, my first showroom was already established under the name Allegro Audio – it was located in Eger and operated from 2015. Since 2016, Allegro Audio has operated as a distributor of REGA, Chario and other brands, while in 2018 a new showroom in Budapest was open.

I had come up with an idea of an amplifier that would also be capable of satisfying my own musical needs many years ago. I started bringing it to life in 2017, when the Flow by Allegro brand was established. Right then, my amplifier took on its today’s form, through many experiments, research, trials, and tests. The development is still in progress – me and my wife, who has been my business partner since 2016, have had the ambition to create a final “product” that could be introduced into the market and start its international journey.

All our partners who have listened to the amplifier have had very good opinions of it, including Mario Marcello Murace, the founder and creator of the Chario Loudspeakers brand, or Miroslav Popovich, the manufacturer of WAY Cables from Serbia. They listened to it and were fascinated with it.

⸜ Allegro Audio workshop

WP Let us clarify the nomenclature – the company's name is Allegro Audio, while Flow by Allegro is a brand name?
BT Exactly – Allegro Audio is the name of the company which includes the amplifier manufacturer FLOWMADE. Flow by Allegro is a brand name.

WP What are the major technologies you use?
BT The basis for my amps is the meticulous manual construction process, from selecting and pairing all parts, through implementing all the components on a panel, to assembling the main elements. Measurements of all the components are very important. We also put a lot of emphasis on care, purity and assembly accuracy. After the assembly, there comes the time for the main stages of the process, i.e. measurements and listening tests, conducted separately for each device.

As for subcontracting, we have been collaborating with several Hungarian companies. Surface treatment, housing painting and front panel construction are very important to us. After a long time, we have managed to find professionals whose work is of acceptable quality to us.


IN PRESS MATERIALS, the Hungarian manufacturer emphasizes:

After describing technical parameters, it is essential to emphasize that during the design, development and production of the FLOW by Allegro integrated amplifier, we have always placed high fidelity sound, overall audio experience and connectivity of the device before its technical specifications. Serving and faithful rendering of MUSIC comes before sheer (measurement – Editor's note) test results.

Flow By Allegro, the brand belonging to the Allegro Audio company, now offers three amps: Flow One, Flow Two and Flow Three. They differ regarding their size, output power and circuit complexity, but they share a characteristic visual design, mainly the wooden front panel that features nothing but a LED display. The front is not smooth, but shaped like a wave in accordance with the company's name. The front panel can be made of manually polished, semi-matt Brazilian nut wood or supplied with high-gloss varnish (for an additional fee).

The Flow One amp that we tested is an integrated amplifier with an AB class push-pull transistor output stage and dual-mono topology, i.e. separate amplification and power supply circuits for each of the channels. Let me add that MOSFET field effect transistors are used in the amplification circuitry.

A 400 W toroidal transformer allows to obtain 80 W at 8 Ω and 140 W at 4 Ω. This is not "rigid" power doubling at a 50% impedance drop, but it is a very good result. The distortion level and SNR, 0.06% and 96 dB, respectively, are good but not outstanding, which would confirm what is featured in the press materials of the Hungarian manufacturer i.e. the dominance of listening tests over measurements.

The most important electronic companies in the world, e.g. the American manufacturer DAN D’AGOSTINO MASTER AUDIO SYSTEMS, share a similar approach. Its owner, who has given his name to the company, made the following comment for the “Stereophile” magazine:

What I always say is that our equipment measures adequately. The measurements are good and respectable. But we're not looking for measurements. […] in my experience of 40 some years, low distortion never makes it sound better. Ever.

⸜ JASON VICTOR SERINUS, D’Agostino Progression M550, “Stereophile”, November 2021, Vol. 44, No. 11, p. 53.

Neither Teleki, nor even D’Agostino have been the first ones to have come up with this conclusion – other companies had done this before. However, it can be clearly seen that such a way of thinking has entered the audio mainstream and using semiconductor elements today is not synonymous with striving to achieve the lowest distortion possible. A lot of manufacturers are rather trying to reduce their impact on the amplification circuit and achieve the end results in a series of listening tests. One of the most frequently chosen options of sound improvement which, however, results in higher distortion, is giving up feedback. This alternative has been opted for both the aforementioned American manufacturer and the Allegro Audio company presented here.

The Flow One amp is a large and rather heavy device which makes a big impression. It measures 440 x 200 x 430 mm and weighs 25 kg. It is untypically placed on three wooden flat cones (two at the front). It is sent to us in a nice wooden case where we will also find a wooden and really cool remote control. The remote only features volume level, input, mute and standby buttons.

The tested device is a classic analog amplifier without a D/A converter, file player, Bluetooth connectivity, or a multi-room system. It does not include a headphone amplifier or a phono stage, either. It features four high-quality RCA inputs and equally good WBT nextGen speaker terminals. The red LED display shows the selected input and volume level. The latter is controlled by a discrete circuit with relay switched resistors – the attenuator offers sixty-three 1 dB steps.


⸤ THE WAY WE LISTENED The Flow One amplifier stood at its own feet on the upper shelf of the Finite Elemente Master Reference Pagode Edition MkII rack.

The Flow One was connected to Harbeth M40.1 loudspeakers using Siltech Triple Crown speaker cables. The signal source was the SACD Ayon Audio CD-35 HF Edition player, through Siltech Triple Crown interconnects. Power was supplied using the AC Harmonix X-DC350M2R IMPROVED-VERSION power cable connected to the Acoustic Revive RTP-4eu Ultimate power strip.

Albums used in the test | a selection

⸜ KRAFTWERK, Minimum-Maximum, Kling-Klang Produkt/EMI 3349962, 2 x SACD/CD (2005).
⸜ Jean-Michel Jarre, Electronica. Vol. 1: The Time Machine, Sony Music Labels SICP-30788, BSCD2 (2015);
⸜ PAT METHENY, Bright Size Life, ECM Records/Tower Records | Universal Music LLC PROZ-1091, „ECM SA-CD Hybrid Selection”, SACD/CD (1976/2017).
⸜ PATRICIA BARBER, Companion, Premonition Records/Mobile Fidelity Sound Lab UDSACD 2023, SACD/CD (1999/2003);
⸜ LEONARD COHEN, Popular Problems, Sony Music Labels SICP-4329, CD (2014);
⸜ ULTRAVOX, Quartet, Chrysalis Records CDP32 1394-2, CD (1982/1983).

IF WE PLACED the ultra-warm sound of the reference system or the DAN D’AGOSTINO PROGRESSION INTEGRATED amp, saturated with harmonics, at one extreme, and the equally saturated but much more clearly “controlled” sound of the Circle Labs two-piece P300& M200 system from the cover of the December issue of HIGH FIDELITY at the other extreme, the Hungarian Flow One would be situated right in the middle between them. On the one hand, its sound retains a lot of the warmth and saturation that we most frequently attribute to class A, or to a lack of feedback, and also often to tubes. On the other hand, the warmth and saturation have been placed in clearly defined frames.

I started the listening session with PATRICIA BARBER'S and PAT METHENY'S albums, as the owners of Flow by Allegro are their big fans. They have recently attended a concert of the former artist and are going to attend a concert of the latter. The double bass on the Companion album was outstandingly competent, as it was very well articulated, pure, fast and well controlled. The bass guitar from Bright Size Life sounded equally good. Both instruments were large, dense, but mostly wonderfully defined. It was really clear – oh yes, it was! – that the Hungarian amp excellently handles the quite difficult load of the Harbeth M40.1 loudspeakers.

Thanks to that, the amp shows large or even very large, deep and tangible instruments and vocals. The lower midrange is not as saturated as in the reference amplifier, but, on the other hand, it is a bit stronger than in the Polish two-piece Circle Labs amplifier. It is the depth, however, that attracts our attention. The keyboard from LEONARD COHEN'S album Popular Problems, bass and choirs were shown by Flow One in a wonderful three-dimensional way against a dark “background”.

I have no doubt that the device offers high resolution, but it does not move towards analysis. When we listen to not-too-well-recorded Cohen's vocal, we do not get lockjaw like with many accurate products that lack intuition. The tested device shows that the designer wanted to combine fullness with simply pleasant sound that would allow for long listening sessions. Unlike in warm (usually tube) systems, but not only, in this case sound dynamics does not “collapse”. On the contrary, it is excellent.

While undeniably warm amps leave a sweet aftertaste in our mouth, like after we have eaten a spoon of honey, the Flow One makes us feel as if we have drunk wine from the Tokaj region – still sweet, but more sophisticated. That is why albums that were not that well recorded will not be “overexposed”. It should be known that this is an accurate, but at the same time somewhat forgiving amplifier which makes listening easier. Even the first digital issues of analog material, such as the ULTRAVOX Quartet album released in 1983, sounded fluid, smooth and almost velvety.

| Our albums

⸜ ULTRAVOX Quartet

Chrysalis Records CDP32 1394-2
COMPACT DISC (1982/1983)

THE ALBUM QUARTET WAS the sixth one by the British ULTRAVOX band, whose music is most often associated with the new wave genre. Released on September 15, 1982, it did well on the charts and, already in December that year, the British record association awarded it the gold record status for selling 100,000 albums.

Quartet was some kind of a new opening for the band. After three albums produced by Conny Plank, the German musician and producer responsible for creating and popularizing krautrock music (Neu!, Kraftwerk, Harmonia), Ultravox asked someone who had not been an obvious choice to cooperate with them. That person was GEORGE MARTIN, i.e. the co-creator of The Beatles' success. That was not an obvious choice because sir Martin did not like pop music and was in love with classical music.

As it appears, the collaboration had been arranged by the producer's daughter who was a big fan of the Ultavox band, while Martin not only significantly changed the process of Midge Ure's vocal production, but halso had an impact on the arrangement and music itself. The recordings were made at the AIR Studios in Oxford Circus, while the mix and mastering were made at Montserrat studios. Let me remind you that the latter were located at a tiny East Caribbean island belonging to the British Overseas Territories, where Dire Straits Brothers in Arms album was recorded two years later.

The AIR Studios, co-owned by Martin, were trailblazers in 24-track recording. They were also equipped with a 58-channel Neve mixing console. The same console, MCI multi-track and Ampex mastering tape recorders as well as JBL and Tannoy speakers were also used at the Caribbean studio, which made work easier. Recordings for Quartet were most probably made at Studio Two, the smaller of the two.

The album version that I would like to recommend to you is the oldest digital issue. The LP and cassette were released in 1982, the CD a year later, while the remasters come from the years 1998 and 2009, when the 2-disc edition was issued. However, the first issue is very good, while the one I am recommending, mastered by the independent Nimbus Records company specializing in high-quality discs and LP reissues, is even better.

THE ALBUM PRODUCED BY GEORGE MARTIN was not overly loaded, as it does not feature too much bass. The tested amplifier really nicely showed its softness and a lack of aggressive compression, which is a bit problematic on the following remasters. There was smooth treble, but it was well-accented and defined. This was already audible at the very beginning of the album, when we hear electronic percussion plates close to us, on the listening axis.

Whatever we say, the greatest impression is made by the way the tested device creates the event. It is because it does not show music as a static arrangement of sounds, but as a composition changing in time, with accurate dynamic shading and a large sound stage. “Impetus” is the word which often came to my mind, also while I was listening to LED ZEPPELIN'S Dazed and Confused, where I got enormous space with wonderfully marked planes, differentiated with regards to tone color and dynamics.

There is something about Flow One's sound that makes the created world seem full and finite. And it does not matter if it is acoustic bass from Barber's album, Johnny Bonham's percussion, or the engine sound opening the track Autobahn from KRAFTWERK'S concert album Minimum-Maximum. Each of these elements featured very well saturated tone color and was set at deep bass. The bass neither went as low as in the reference system, nor was it that well differentiated. This is understandable, however. Compared to other amps from the same price range, the Flow One will shine in terms of going down the scale and differentiating that part of the range.


A PRODUCT SOLD AT A CERTAIN PRICE has its limitations. It is so – and if someone says anything different, it is better not to listen to them, as they probably want to deceive us. So, using the same oenological analogy, if the reference system was Tokaji Aszu Eszencia, the Flow One would be Tokaji 5 Puttonyos, i.e. one that is not that rare, not that refined, but still perfect.

The Hungarian amplifier has everything that we expect from high-end products, i.e. internally complex sound with great tone color, certain sweetness allowing us to listen to every kind of music, but also high dynamics. It also builds enormous three-dimensional space. Thanks to it, recordings such as Zero Gravity, from JEAN-MICHEL JARRE'S Electronica. Vol. 1: The Time Machine, issued on Blu-spec CD2 by Sony Music Japan, will sound spectacular in their impetus and apparent lack of limitations.

The amplifier also shows large stable vocals without merging them with the background, even if the mixer (engineer) placed them far at the back, like on the Led Zeppelin's album. The Flow One will show where they are situated, but will not extinguish them or limit their role to a background for instruments. It is well-developed, really nice, engaging, large sound. Let us add loudspeakers such as Chario or Harbeth to the amp, and we will have an exceptionally exciting audio system at home.


THE MOST IMPORTANT INFORMATION ON THE LOOKS AND FEATURES OF THE AMP can be found in the first part of the test, so we will not repeat it here. Let me just add that the display where we can see the selected input and volume level, where ‘0’ corresponds to silence and ‘61’ to the maximum volume level, dims a moment after we make the change, without irritating the user's eyes. The RCA inputs are also well thought-out, which are set apart so far away from one another that we can use any interconnects. The back panel also features an IEC power socket with a switch and a ground terminal. The former features a red dot showing polarization – it is worth remembering about that!

⸜ THE INTERIOR The Flow One is a semiconductor transistor design with a passive preamp. The preamp is mounted on a small PCB, directly attached to the board with RCA inputs. The attenuator features precise Dale transistors and Japanese relays. The company's very good resistors have also been used in the power amplifiers attached directly to radiators on both sides of the housing. The upper panel made of thick steel plate has been dampened using bituminous mats – a similar mat is placed under the power transformer.

There are six pairs of complementary MOSFET transistors in the push-pull mode. I was not able to check what transistor models these are. The PCB features only high-quality components. It is similar with the power supply. Its part, stabilizing voltage for the pre-stage, has been placed next to the attenuator, while the other one directly on the power amplifier circuit boards – there we will find eight superb Vishay capacitors filtrating network hum.

The manufacturer talks about dual-mono design and it is actually true. Rectifier bridges, blocked by Vishay capacitors, are separate for each channel. Power transformer secondary windings are also separate. The transformer itself is single, however; it had been wound by the Hungarian company Tortek Elektronik. The element that shields it features the information that it was made according to a specification provided by Flow by Allegro. It looks really robust. Let us add that signal to speaker terminals is sent using quite long cables by the French Viard Audio manufacturer, from the HD-line series.

The amp's design is fairly simple but well thought-out, and the device is wonderfully made.

Technical specifications (according to the manufacturer):

Rated output power: 80 W/8 Ω | 140 W/4 Ω
Frequency response: 20 Hz – 20 kHz
THD + Noise: <0.06%
SNR (Signal Noise Ratio): 96 dB
Power consumption: 400 W (max) | 75 W (standby)
Dimensions (W x H x D): 440 x 200 x 430 mm
Weight: 25 kg
Finish: manually polished semi-matt Brazilian nut wood or high-gloss varnish (for an additional fee).


Reference system 2021

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