Audio Alto AA EN 1000 High power amplifier energizer review

I’m always (yes, still) thrilled when something interesting lands at the Mono & Stereo nest. This time arrived the Audio Alto AA EN 1000 High power amplifier energizer, that brings 9x of the power of the connected amplifier. Idea is to energies the low powered tube and solid state amplifiers without loosing the original sound.

The AA EN 1000 (Energizer) is a new product that energizes the attached master amplifier output power by implementing very unique circuits and special approach. The idea is that AA EN 1000 takes the master amplifier signal without altering it and then passes the signal directly to the attach speakers. Beyond this, the Energizer, being connected in parallel with the master amplifier, adds the required current and voltage in harmony with the master amplifier output to energize its raw power. Adding AA EN 1000 to existing system leaves the master amplifier audio signature unchanged although the power on attach speakers is nine times (review model9x) larger.

I’m more then sure then many of you will instantly recall Music Fidelity Superchargers. Quick observation might put them under the same label, but Superchargers was actually a booster with 50 Ohm input and as such they acted with same burden for the masters amplifier. In this way, beside the preamplifier, master amplifier performed all the duties with its own character.

EN1000 operates a bit different in parallel and depending on the internal configuration, that will be explained further on and can be set to 2x, 3x, 4x, 8x etc. factor of the amplifying, (depending on the implementation in the system) acts more in the realms of energy balance transfer.


I’ve couldn't resist trying Audio Alto AA EN 1000 High power amplifier energizer upon arrival. From my hands into the listening room and straight into the system. There were no doubts upon first notes coming into the play. The impact was instantly recognizable, with volume turned down by almost third on my Robert Koda Takumi K-10 preamplifier. We’re not talking about subtleness. Instantly the locking grip took place with a mighty power output, that literary grabbed speakers by their guts. It kept the master amplifier qualities and conveyed the music energy analogous to natural energy transfer. Good example would be something we can experience in nature, for example the waiter flow, that is guided through a dedicated canal. It keeps its original impact, but gains enormous power when forwarded through the new course.


To understand better the inner workings of AA EN 1000 I’ve asked Audio Alto’s Saša Burian few questions about his new product…

Where comes the idea for AA EN 1000?

A lot of music enthusiasts own a sweet and less powerful amplifier. They are used to it, sometimes also in »love« with it and they like the sound and the reproduction. Listening to more dynamic music or maybe changing the speakers means that they would need more power. My idea was, that if I could develop a "box", that will deliver more power and keep the sound (the sound signature) of the loved amplifier unchanged, the user will be able to keep it and fulfill his/her wishes about dynamics/power and sound. So the "box" should not be a typical booster and should allow the target amplifier to deliver its sound and power to the attached speakers. The conclusion was that the new "box" should work in parallel with the target amplifier. So I developed the »energizer« AA EN 1000.

How does AA EN 1000 differ from what Musical Fidelity did in the past?

Musical fidelity 550K Supercharger was a typical booster amplifier or let say, a power amplifier that the input was designed to be connected to the output of a smaller power amplifier instead of typical preamplifier output. As I mentioned before the AA EN 1000 works in parallel with the target amplifier, helping and providing it with required additional current (and voltage).

Can you describe the exact operation?

The EN 1000 is basically a powerful power amplifier with a 1200W power supply (or 2x 1200W in dual mono configuration) and with 4x 500W power amplifiers working in bridge configuration. They can be used as a typical amplifier that will produce very low distortion with high damping factor and very neutral sound. To change the configuration to the »energizer« mode I developed a circuit (module) that monitors the target amplifier current and voltage and in parallel with it delivers the additional required current (and if required - voltage). The power increment can be set to different factors (ie 2x, 3x, 4x, 8x...) that are configured during production process depending on customer wishes and requirements.

Is one EN 1000 enough or it depends on the setup?

The one box EN 1000 is a member of energizer family that delivers up to 2x 500W or in a dual mono model 2x 1000W. If a customer would like to increase power of two smaller mono blocks the setup probably should use two energizers. Depending on the target amplifier the energizer can be also a smaller model (i.e. EN 200 that will deliver up to 2x 200W).

How does AA EN 1000 differ from typical power amplifier?

The AA EN 1000 is a high power amplifier with very low, without typical class A/B, cross over distortion. If used in this mode its sound is precise and very neutral. When used as an »energizer« amplifier the technical characteristics are unchanged and I would say also required, as only with such features the energizer can add power without altering the sound signature of the target amplifier.

Operating in A, AB class or?

As the enclosure size is small for delivered power the modules are high quality, high efficiency analog amplifiers working in class D (Hypex NCore OEM modules). The power supplies are SMPS modules.

Does it act in the same way with tube and solid state amplifiers?

Yes, it doesn’t matter what kind of target amplifier is working with. The only parameter that is important is if the output of the target amplifier is in bridged configuration. In this case the dual mono or two boxes energizer model is (are) required.

Who would you recommend it?

I would say that if the music lover sometimes, while listening to favorite music, thinks about or feels that the dynamics, low bass energy and the sound stage should be bigger, is worth to try the energizer (i.e. AA EN 1000 or other family members). He/her will be amassed how his/her “loved” amplifier could sound with the help of the energizer…


Connecting the AA EN 1000 was no brainer. You simply connect speakers outputs of the master amplifier with AA EN 1000 forward them to speakers from the Energizer.

I’ve tried the Energizer with different amplifiers, but for sure most interesting part of its operation and intended purpose is to add power where is most needed; low powered amplifiers. For this scenario great sounding tube power amplifier from the Land Of The Rising Sun fitted perfectly.

There was no push forward character coming from AA EN 1000 when connected to the 12W Yamamoto A03-S tube power amplifier. It felt like AA EN 1000 keeps the original character at its own realms while adding grand power.

We cannot call about ultimate purity as anything of electrical behavior adds a scent of its own taste and there are always different cables in play that combine its own portion.

Still, we’re are talking about minor, subtle imprint that never comes as forte. Do note that this version of AA EN 1000 comes with 9th power. Depending on the speaker in play this can scale down in a grand way. For most applications 2x, 4x might be of perfect balance and the more you go down with the power, the less of character will be in notion.


Everything can be technically explained and layed down, but without music in motion all is more or less senseless.

I’ve stressed out, AA EN 1000 with both digital and analog formats. There are always quite few track and albums in reference rotation evaluation, but its always great to note at least some pin pointing.

The most important question with specific and particular device like AA EN 1000 is what happens across the musical genres. There are always different expectations with any genre followers, yet the objective substance should be of same building blocks.

Doug Macleod - Come To Find

Surely both audiophile and music lover classic. There is color palleting with Come To Find. The impact falls into the area of black and white. If the system or product under review can keep Doug’s grip and energy it passes. If not there is something other squeezing the energy essence.

Audio Alto’s energizer followed the rules on engagement with ease and without self imposing. Mission accomplished!

Berlioz - Ataúlfo Argenta - The Paris Conservatoire Orchestra ‎– Symphonie Fantastique Op. 14

Fantastique in every sense of the word. Sensual, intuitive and emotionally charged. Its hard to imagine that Berlioz composed this masterpiece way back in 1830.

Interplay of rondo mood swings explores the complex human nature and act like one of the kind emotional journey.

Diversity of music remarkably conducted under baton of Ataúlfo Argenta represent a grand intake for any amplifier.

When it comes to the speed of the sound it's not only about speeding and slowing down. At any point music is much more complex at its core and while getting the information across the board might be seen as pedestrian sonic entourage, the rendition of this classic composition demands endured “electrical” multiplexing.

Energizer expertly embraced the needed forte without limiting the musical movement varieties and managed to expose the drama in absence of abbreviated form, that can too quickly limit the sonic performance.


With the resurgence of low powered tube amplifiers as well as SIT?, solid state pure A class amplifiers and on the other side multitude of of hungry power dynamic speakers one cannot call demand for high quality, more power effect amplifiers a niche market anymore.

In the real world, all of above mentioned design comes as mandatory with non sufficient power output. Climbing up the ladder add significant, hefty price and even lesser products to choose from.

This is where Audio Alto AA EN 1000 kicks in a bold way. Called it a 21st century solution or even the healthy remedy for the lacking power.

People in general loves going back to the purity and simpler amplifier solutions. For many the low power represent unavoidable fact and problem, but by default they don’t want to loose the power of refined circuits.

The flexibility of AA EN 1000 internal setting opens up the world of proper real world application of these devices.

AA EN 1000 hit the market at the right time and with the right price. Its not inexpensive, but compared to what you’ll have to pay for some exotic, higher powered class A amplifiers this is a bargain. Its a product that comes as long term investment and not one day trick pony; something you’ll feel urged to exchange anytime soon.

Saša Burian decades of exploring different designs and concepts materializes in unique and potent high-end audio product, that found its place in the vast market of Déjà vu’s.

The slim, practical shape takes little space and can fits most audio racks without a problem.

Audio Alto AA EN 1000 is a little giant, with a mighty healthy hearth.

I’m wholeheartedly handing out Mono & Stereo Highly Recommended Award for what it accomplish and what it can offer.

Matej Isak


EN1000 – 4.950€ (VAT excluded)


· Frequency response: 0 Hz to 50.000 Hz -3dB 
· Distortion: < 0.005 % at 300W 
· Noise: -114 dB 
· Output Power: 2 x 500W @ 4 or 8 Ohms 
· Input: 2x 1 to 55W @ 4 or 8 Ohms 
· Dimensions (W x D x H): 295 x 465 x 93 mm 
· Weight: 11 Kg 
· Finish: Dark Shadow, Silver, Inox, Chrome, natural solid wood (i.e. walnut) or upon special order in various colors


Audio Alto
SBBS Plus d.o.o.
Valvasorjeva 12
1000 Ljubljana

phone: +386 1 438 47 85, +386 41 399 256 
fax: +386 1 433 91 96