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Teresonic Reference 2a3 Integrated Tube Amplifier Review

Limited Edition

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Teresonic Reference 2a3 Limited Edition Integrated Amplifier

Another Accidental Discovery And A Little Personal History

If you happened to read my review of the Ikonoklast Model 3 speakers, you know how I accidentally discovered them while traveling around comparing the VSEI modded Sony SACD players to good turntables. Well it has happened again. I went by to pick up the Teresonic Integrum JL’s from Mike Zivkovic, the president and founder of Teresonic. He asked me to go in and hear them first. He wanted me to hear what they sounded like when correctly set up, I was shocked by the sheer volume and scale they were capable of. I asked about the beautiful black and gold amp that he was using. I was shocked again. It was hard to believe the big amplifier had the huge output of 2.5 watts. You read that right: not 25, but 2.5 watts. It was Teresonic’s custom-made 2a3 amp.

I have been using SETs for about 15 years. I have mostly used 300B amps, but I have also used 845s and PX25s. Before the SETs, my favorite amps were a pair of stereo Beard 35s. They used eight EL84s each and put out 35 watts per channel. I used them to vertically bi-amp an assortment of speakers. What I have never tried until now are the truly flea-power amps. I guess I never thought I would have speakers to play them on.
Anyway, as I was finishing the review of the Teresonic’s Integrum JL’s I had an idea. I called Mike and ask if he could bring the amp over and leave it for a while, so I could comment on how the Integrum JL’s sounded with 2.5 watts as well as the 8 watts I had been using them with. So began my education about the sound of 2a3 amps.


The Teresonic Reference 2a3 amp is as beautiful to look at and as it is to listen to. It is designed with no capacitors in the audio circuitry, like my Wavac EC300B. It is an all tubed design including tube rectification. It uses New Old Stock tubes made by RCA mostly in 1940’s and 1950’s, such as the NOS RCA 6SN7, 2a3, and 83 rectifier tubes. The tubes are mounted in low-noise, gold plated, ceramic tube sockets, and the sockets are insulated from the chassis using vibration damping material to protect the tubes from any vibrations.

These Teresonic amplifiers are each carefully handmade to order with the best new or NOS components available, such as Riken resistors, Black Gate and Mundorf capacitors. The amps have silver wiring all the way through. The output and interstage transformers are made by Lundhal of Sweden. Mike thinks they make some of the most natural-sounding and detailed-sounding iron on the market. These transformers were also chosen for their dynamic, lifelike aliveness.

On the high-gloss black front panel you will find four big gold rotary controls. From left to right, they are the HEATING POWER ON/OFF, HIGH-VOLTAGE ON/OFF, VOLUME and SELECTOR switch for the four line sources. In the middle is the Teresonic name in a soft blue LED. Red LEDs indicate power status and selected line source. There are four RCA inputs and one pair of symmetrical XLR’s for maximum flexibility in connection choices. The inputs are on the right side of the chassis, while the WBT speaker connectors are on the back. The build quality of the Reference 2a3 is superb; it should last a satisfied owner for a lifetime.

Design Goals

Teresonic set out to design the Reference 2a3 with a goal of building an amp with the highest sonic performance possible, for use with high-efficiency, full-range speakers such as Teresonic’s own speakers. They settled on an SET design with a minimum number of ultra-high quality components. They hoped to establish new standards in natural, detailed sound with sweeping stereo imaging, tonal richness and no coloration. The output tube they chose for this amp was the classic 2a3.

The Tubes

Mike would only consider NOS tubes, and I know of no other 2a3 amp that comes stock with tubes like these. Tubes like these are hard to find, expensive and well worth all the effort and money. I have found the same to be true for my Wavac; Ken Shindo literally designs amps and preamps around great NOS tubes he discovers. So, don’t underestimate the importance of the tubes that the people at Teresonic go to the trouble of finding to use.


I simply set it up next to my amp. I unplugged from my amp and plugged into the Teresonic the interconnects and speaker cables. Then I turned the warm up switch, or as they call it the “HEATING POWER” switch on. I let it warm up for about an hour and came back to listen. For all the listening I used the Clearaudio Anniversary Reference table with either the Clearaudio Satisfy tonearm with the Micro-Benz Ebony TR cartridge. I also occasionally used the Slim Devices Transporter with an Audio Note Dac for a digital source. The preamp was the Shindo Masseto, and the speakers were either the Teresonic Integrums, Ingeniums (in for review), or the new Ikonoklast 3HOs. I tried cable from Audience, Auditorium 23, and Nordost, but I settle on Teresonic’s own Clarison cables.

The Sound

I want to admit I was surprised by the basic difference in sound from the Teresonic 2a3 amp and the Wavac EC300B amp. They both have NOS tubes, except the 300Bs in the Wavac are the newest Western Electrics from the Alabama plant. I think they sound best of all 300Bs I have heard. I don’t think it would be accurate to think this is the same differences you would hear in a comparison of most 300B versus 2a3 amps. The reason I say this is because the Wavac EC300B sounds like no other 300B amp I have ever heard, and I expected, with the design described above, the Teresonic 2a3 would sound quite a bit different than a typical 2a3 amp.

The Bass

Probably the first thing you will notice about this amp is its bass. It has more power in the lower octaves than my Wavac. No, it’s not as quick or as nimble, but it is powerful like live music can be sometimes.

Along with that power in the bass, you can still hear the tonal colors, the pitch definition, and more of it follows the initial impact of the leading edge of bass instruments. With drums, you don’t get quite the initial impact of the stick hitting the skin; but the thunder of the drum and the air that moves with the mighty strikes of big drums is amazing. Likewise on stand-up basses and cellos the leading edge is not quite as there as it is with the EC300B, but the sound of the wooden bodies with the air moving in them is really beautiful. Both amps do an incredible job of letting you hear the space around the instrument and the decay and echo so naturally.

The overall sound of the Teresonic 2a3s is a punchy and detailed bass that goes very deep. The SET has great pace, rhythm and timing, better than transistor amps in this regard. This little amp with its 2.5 watts will startle you when there is real bass on a recording and keep you patting your foot as well.

The Midrange

This is the glory of all the SETs I have heard, especially 300B powered SETs. The Wavac 300B amps are incredibly transparent with beautifully detailed midranges. I am afraid I am somewhat addicted to them. The Teresonic 2a3’s midrange may not be quite as transparent as the Wavac EC300B, but it has a wonderfully natural, relaxed, liquid, sweet and warm midrange. Sinatra, Ella, or Ben Webster’s sax all sounded so relaxed and effortless through this fine-example of a flea-power tube power amp. You can hear layers of tones and textures come out of a very natural sounding background of silence. This amp sounds quite involving and moving at both low and loud listening levels. It has the capability to let you hear just the right amount of lushness from the strings and woodwinds, without being too warm. When you combine this midrange with the bass I talked about above, you have a real winner on your hands.

For me, it is always the midrange that I find the most difficult to describe. The Teresonic 2a3, like the Wavac and Shindo amps, can breathe life into recorded music so as to give you the feeling that you are listening to music being played by real people rather than listening to a great recording on a great stereo. It also delivers the emotive message of the music in a powerfully involving way. This amp allows the differences from one instrument to another to be heard with ease. When listening to a trio of guitars or the backup singers, it allows you to hear each one in their own space.

Combined with a speaker that doesn’t store up any bass energy of their own, like Teresonic’s own or the Ikonoklast speakers, the 2a3 produces a purity of sound in the lower midrange that allows plucked strings, drum strikes, and other upper bass transients to be startlingly alive and natural.

The Top-end

I never seem to write as much about the top-end of a product. Maybe that’s because to me the best thing one can say about the top-end of any audio product is, “I didn’t notice it”. Yet, I always notice when something is lacking in air or sparkle. I also think everybody notices if the top-end is bright or tilted up in relationship to the midrange. When the top-end is right, though, I tend just to listen to the music.

This is exactly the problem I have with describing the top-end of the Teresonic. The 2a3’s top-end is open, sweet, and to me just easy to listen to. It allows the music to come to life in a way that just sparkles with musical realism and does nothing to distract me from the musical performance I am listening to; it is absolutely never analytical or etched sounding.

Soundstage and Imaging

The Teresonic 2a3 has as a wide and deep soundstage, but achieving an audiophile soundstage is not what this amp is all about; it sort of misses the point. It has a very good soundstage that does not draw attention to itself; what will make you not miss the specifics though is that its soundstage has awesome scale. I don’t know why musicians love to walk over and stick their horns right into the mic, but they do and that larger-than-life sound is part of a live Jazz performance, and the Teresonic amp and speakers can let you hear that in a most realistic way. I want to hear a vocal or a trumpet start soft and small, then swell in volume and size as they reach back and let it go. Again, the Teresonic amp and speakers do this beautifully.

Another thing I want to hear in a natural soundstage is space and air around, and even within an instrument. I’ve said this from my first Teresonic review but, I just don’t want strings floating around in some black velvet space like a modern painting that show strings and notes but no instrument or musician. I want to hear the body of the guitar, I want to hear the floor under the bass, I want to hear the sound of the strings inside a piano. And, once again this system can do that.

A Few Examples

Ever since the movie Ray, I have been back into Ray Charles. I am so thankful for the original copies, both stereo and mono ones that I have of the 1961 Ray Charles and Betty Carter album. With the Teresonic 2a3, it was lush-sounding, warm and mellow, which is appropriate for a recording of songs about love and romance. I love the way the horns and drums jump right into the performance. With this amp, the horns have just the appropriate amount of bite, and when the piano comes in, it has just the right amount of warmth and reverb. Ray’s and Betty’s voices were tonally correct with no trace of exaggerated sibilance.

Mary Lou Lord’s Live City Sounds is such a simple recording. It’s just here accompanied only by her own guitar. That’s right, just her voice and a guitar recorded in the New York subway. I love the cut “’52 Vincent Black Lighting”. Though it’s just her and an acoustic guitar, it’s still so explosive, so emotional, yet so natural and relaxed at the same time. With an amp like this and the Teresonic speakers, you can feel the emotion of her voice, the power of the strings, the warmth of the guitar body. This is about as far from an audiophile recording as you can get, but the Teresonic 2a3 allows me to really get into it. I think what allows it to be so emotionally involving is how the subtle details flow. Yes, you can hear in her breathing and phrasing, but the rhythm of her voice and the guitar just flow into your room.

Willie Nelson is popular around my house and he offers a lot to listen for in regard to differences in textures, and harmonics. I don’t want my system to make Willie sound like some lesser singer singing when he does that thing he does with his voice and guitar. With the Teresonic 2a3, you can hear and feel the difference in the emotions and phrasing when he is singing and playing. This is what I want in an amp. I want to be able to listen deep into music, it’s layers, timbers, harmonics, and feelings. All of this is easy with this amp in my system.


The Teresonic Reference 2a3 Limited Edition Integrated Amplifier is definitely an all-out, price-no-object 2a3 amp. This 2A3 amp has a very open, relaxed, dynamic and detailed sound. It allows you to experience music in an extraordinarily emotional fashion with a holographic soundstage.

This amplifier, like the Wavacs and the Shindos, is the real thing. It brings you so close to the real thing you won’t believe it. It is among the best amplifiers I’ve ever heard, and it has the build quality to match. Admittedly, most of us can’t spend 15 grand on a single piece of audio equipment. For that price, you get extraordinary quality and performance, the best quality parts Mike can find, the best NOS tubes available, and they are entirely hand made to order. I think when you consider all of that, this flea-power amp is fairly priced.

Manufacturer’s Comment:

We, the Teresonic team, would like to express our sincere gratitude to Dagogo and Jack Roberts for a thorough and insightful review of the Reference 2a3 amplifier. While most of the industry is spending efforts on developing megawatt amplifiers that consume huge amounts of energy to drive ever more inefficient loudspeakers – we at Teresonic are taking a different approach. Our efforts are invested in creating ultra-high efficiency, ultra-high quality speakers capable of producing natural-sounding music even with (very) low-power amplifiers. No technical explanations are necessary to understand how much easier and less expensive it is to make top quality low-power amplifiers than high-power ones. That’s how the Reference 2a3 was born – as an example of all the beauty of natural music and energy efficiency to enable “Green Audio” approach to music listening.

As Jack already observed Reference 2a3 wasn’t created as a commercial product to compete with many fine tube amplifiers from Art Audio, Wavac, Blue Note, Red Wine Audio, Manley Labs, Reimyo, etc. many of which are (or will be) reviewed at It was created as a reference standard with Teresonic speakers and cables to demonstrate our commitment to the beauty of natural music. Reference 2a3 is a special order product depending on availability of NOS tubes and other hard-to-find components. We will not cut corners and compromise with replacement parts and apologize in advance if we are not able to accept an order because of parts unavailability. Fortunately, many products from companies mentioned above are very fine ones indeed and work very well with Teresonic speakers and cables to let you enjoy naturally sounding music. Isn’t that what matters after all?

The Teresonic Team

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