Hold the Feedback

Listening Room Confidential, No. 4 — an occasional series.

Two rebels walk into a hotel room. One is Soulnote, a Japanese electronics maker that has thrown out negative feedback. The other is Guru, a Swedish loudspeaker maker that wants its speakers pushed up against the wall. Between them, that's two of the hobby's commandments broken before lunch.

At the Toronto Audiofest, October 16–18, the Soulnote A1v2 and D1v2 will be driving Guru loudspeakers: more modestly priced designs engineered to live near a wall, in rooms with furniture and people in them. The pairing is deliberate: Soulnote's more attainable electronics meet Guru's more modestly priced speakers, the sort of system a person might actually take home.

I'll explain the thinking, then get out of the way and let the music do the bragging, which is the proper order of things. No sides to pick, no sermons. Just a reason to sit down and listen.

The measuring cup principle

Every kitchen has two kinds of cook: the one who measures everything and the one who swears by feel. Every kitchen also has one night when they argue over a perfectly good cake while it goes flat. Hi-fi has been having this argument for decades, and we're bringing the cake (figuratively, of course).

A word on all the cooking. Taste and hearing are both human senses, and in both the last word belongs to a person, not an instrument. A scale can tell you a cake contains exactly 200 grams of flour, but not whether anyone will ask for a second slice. A test bench can tell you an amplifier's distortion to three decimal places, but not whether the music makes the hair on your arm stand up. So yes, there will be food references, and they are entirely on purpose. Bring on the food references.

As a broke student, Hideki Kato built amplifiers and speakers by ear alone, with no test equipment, and was thrilled with them. One of them, in his opinion, beat a friend's expensive amplifier. Then he got hold of a measuring device. The numbers were grim, so he did what any conscientious engineer would do and fixed them. The specs improved. The music went flat. Call it the measuring cup principle: follow every measurement to the letter and you can still end up with a flat cake. Kato reaches for the kitchen himself: weigh every ingredient to a ten-thousandth of a gram, he says, and a world-famous chef's dish will still taste different from his.

Every cook knows that moment: the dish tastes right, the recipe says it shouldn't, and you have to decide who to trust. Kato says the puzzle took him four decades to work through, by way of NEC's audio department and Nippon Marantz, where, happily, he got to work on non-feedback power amplifiers, before he landed at Soulnote as chief engineer in 2016. His conclusions are written up in his own words, translated from Japanese, and worth an evening.

Feedback, in one paragraph

Negative feedback is the amplifier tasting its own cooking and adjusting the seasoning, constantly, while the dish is still on its way to your table. Most amplifiers do it, and it makes the numbers gorgeous. Kato's quibble is that a cook who never stops fiddling can serve you something technically flawless and utterly forgettable. So Soulnote skips it and tunes by listening instead of by meter. He's fond of a sushi analogy: two plates, same fish, same rice, one made by a master and one by an amateur. The lab report says identical. Your mouth disagrees.

To his credit, Kato is candid that this is a hypothesis rather than a proven theory. He's a designer, he says, not a researcher, and Soulnote is his real-world experiment. I find that more persuasive than certainty would be.

Other schools of thought

Not everyone shares Kato's view, and that's healthy. Plenty of respected designers use feedback beautifully, and Luxman, another famous Japanese house, has its own clever middle path that feeds back only the distortion. Even Luxman is candid about the goal: it describes its newer LIFES circuit as delivering a natural sound quality “almost if it were a non-feedback equipped circuit.” Different roads to the same destination. We're not here to convert anyone. We're here to let you taste.

Two boxes, one idea

Sometime around noon on the Friday of the show, a person in a very good jacket will put two fingers on the lid of the A1v2, feel it move, and look at me the way you'd look at a car salesman whose door just came off in your hand. They needn't worry: the chassis is designed to float, the top plate resting lightly on its spikes, because Kato found his amplifiers sounded best with the lid off. It's deliberate, and the amplifier is designed that way.

Underneath, it's a completely non-feedback integrated amplifier built on perfectly balanced, discrete circuits, and it delivers 80 watts per channel into 8 ohms, rising to 120 into 4. Even the volume control follows the philosophy. Instead of a conventional potentiometer, the A1v2 uses a relay-switching balanced attenuator, an approach Soulnote notes is usually reserved for far costlier amplifiers. The rest of the chassis follows the reference models: a symmetrical housing and metallic insulators as standard. It weighs 10 kilos, half the weight of its big sibling the A2v2, so your back will be the first to appreciate the difference.

The D1v2 is the DAC. Most DACs tidy up digital audio with oversampling, a bit like retouching a portrait until the wrinkles and the personality are both gone. The D1v2 offers an alternative called NOS (non-oversampling) that skips it, with the option to switch it back in whenever you like. Two ESS ES9038PRO chips, one per channel, do the converting, and the clock lives inside the box: ultra-low-jitter crystal oscillators, so there's no separate clock to buy or place. The rest of the design, a large toroidal transformer feeding eight independent regulated supplies, is about staying out of their way.

Two boxes. Neither is the flagship. Both are designed the way the flagships are: by ear, without the feedback loop.

The rebel from Stockholm

The second rebel is Guru, founded in Stockholm in 2007 by an engineer, a violinist and an industrial designer, which sounds like the setup to a joke and is in fact a business plan. The engineer, Ingvar Öhman, is a former hearing researcher who couldn't find a loudspeaker accurate enough for his experiments, so he built one. The violinist, Erik Ring, keeps a musician's ear on how real instruments sound, and the designer, Erik Espmark, makes sure the result looks like it belongs in a living room.

And its philosophy rhymes with Kato's. Guru tells you to push the speakers up against the wall, the one thing setup guides have forbidden for as long as I've been in this business. Its manual asks, ideally, for less than five centimetres, barely enough room to lose a remote.

The rhymes keep coming. Both started with a designer who thought the usual yardsticks were missing something; Guru's own technology page notes that a home is nothing like an echo-free chamber and “ears are not measurement microphones.” Both put timing first. Both design for the room the music will actually be played in, which is how a compact cabinet ends up with bass it has no business having. And both look a little odd on the test bench, since a speaker built to sit against a wall seems strange measured out in the open, just as a no-feedback amplifier looks strange on a distortion chart.

Does that make them right? Nobody is claiming it's proven, least of all Kato, who calls his approach a hypothesis, and Guru's case rests more on its designs than on published studies. The mainstream view, built on decades of careful listening tests, has earned its reputation. But notice the question the rebels are really asking: not whether the measurements are wrong, but what is left once they're perfect. Two teams on opposite sides of the world keep circling the same ground: timing, real-world listening and the ear as final judge. That isn't proof. It's the sort of coincidence that makes a person sit up straight in a hotel chair.

The steep part of the curve

Some show systems are built to astonish. This one is built to be taken home. Soulnote's more attainable electronics and Guru's more modestly priced speakers share a philosophy with their bigger siblings, and the question is how much of it survives at a price a person might actually pay.

Think of it as a test of the idea rather than a shopping list. In Has Hi-Fi Lost the Plot?, the first piece in this series, I argued that the first few thousand dollars buy the biggest improvements, and every rung after costs more than the last. That steep early stretch is where most of us live. So come and hear whether the rebels' ideas hold up down here, then decide where your own money belongs.

Your table is waiting

Here is the entire protocol: walk in, find a seat and let the music do the talking. There's nothing to adjust, nothing to ask for and no dress code. Kato's philosophy runs to twelve parts, and there will be no test. No reservation required.

The A1v2 and the D1v2 will be driving the Guru speakers, so the kitchen is open. Stay for a song or two, then ask yourself the one question a spec sheet can't answer: do I want to hear the next one? If the answer is yes, you've just judged the cake by tasting it, which is the whole Soulnote philosophy in one sitting. If it's no, that's a perfectly good way to shop.

We'll be at the Toronto Audiofest, October 16–18, 2026, in Rooms 235 & 237. Come and say hello. Touch the lid if you must. Everybody does. I'll explain.

Follow the series: every instalment is collected under Listening Room Confidential, and the rest of the Notebook lives here.

Next: Did the Rules Survive the Show?, our report back from the Toronto Audiofest.

Previously: How to Listen, Elbows Up, Ears Open and Has Hi-Fi Lost the Plot?.

FAQ in brief

What does “non-NFB” mean?
Non-NFB means no negative feedback: the amplifier doesn't send part of its output back to its input to correct errors. Soulnote leaves it out because its designers believe it costs music some of its life and immediacy, and they tune by listening instead.

Why would a designer leave out negative feedback?
Soulnote's chief designer, Hideki Kato, argues that feedback improves measurements but can take the spark out of the music. Other respected designers take different routes, and Luxman, for instance, feeds back only the distortion. The best way to decide is to listen.

What is NOS mode on a DAC?
NOS stands for non-oversampling. The DAC plays the music as recorded, without the digital oversampling most DACs apply. On the Soulnote D1v2 it's switchable, so you can compare the two sounds yourself.

Does the D1v2 need an external clock?
No. It has ultra-low-jitter crystal oscillators built in, with phase jitter under one picosecond, so there's nothing extra to buy or place.

Will the A1v2 drive my speakers?
It's rated at 80 watts into 8 ohms and 120 watts into 4 ohms, with an output stage designed to supply the instantaneous current real loudspeakers demand. The best test is to hear it with your speakers.

Are the A1v2 and D1v2 a good match for Guru speakers?
They're a natural fit. Soulnote's more attainable A0v2, A1v2 and D1v2 sit comfortably with the more modestly priced Guru 8, 12 and Q10 and the upcoming Elements series, and both brands design by ear, with timing and real-world listening in mind. For the Guru 20, 28 and 42 and the upcoming Apex series, there's room to step up to the A2v2 and D2v2 later.

Where can I hear Soulnote in Canada?
At the Toronto Audiofest, October 16–18, 2026. To find an authorized Audionation dealer near you, contact Audionation. Soulnote is made in Japan and imported directly to Canada duty-free under the CPTPP.

About the author

I've been in and around the audio business for more than forty years. My business card says Founder, which is what you call the person who was in the room before anyone thought to give out titles — hell, before anyone else was in the room at all. Music plays all day, every day, and four decades in, the job is still sitting down and listening to records, or streaming if I don't want to get up. Tell me, what's better than that?

Jeff, Audionation
Founder