Audionet Humboldt Integrated Amplifier

REVIEW
by Matthew Clott
Jul 12, 2021

This review feels very much like an opening act, following the headliner.

In the July/August 2020 issue of TAS, Greg Weaver penned a review of the Audionet Stern linestage and Heisenberg monoblocks, declaring the Scientist Series both the reference-level cat’s meow and pure audiophile shizzle (i.e., he liked them very very much). His review was thorough, well conveyed, and left little to add. Now the Humboldt combines technologies from Audionet’s $150k reference electronics into a huge, and hugely ambitious, integrated amplifier—the $55k Humboldt.

Friedrich Wilhelm Heinrich Alexander Von Humboldt was a Prussian scientist and explorer (1769–1859), who is best known for his analysis and understanding of how plant species are distributed throughout the world. He was a botanist, expert geographer, naturalist, explorer, and polymath. He is considered by some to be the father of ecology, and one of the first great environmentalists. Audionet’s U.S. distributor, Bill Parish of GTT Audio, is none of those things, although I’m pretty sure he has a garden in his backyard. He is, however, a fervent supporter of the company, and has been for many years. I don’t think anyone was more sincerely excited about the Scientist Series introduction than Bill, except maybe Thomas Gessler, Audionet’s International Sales Manager. Thomas’ passion for meticulously crafted audiophile equipment, whose specs settle between untouchable and unmeasurable, is well known in the industry. Audionet’s “Lighthouse” project, begun in 2013, was an all-out assault on what could be achieved, and the obvious first step was a linestage and monoblock amplifier. Enter Stern and Heisenberg. The Humboldt is the logical next step in the model lineup. For those who can’t afford or can’t accommodate separate components, the Humboldt is the solution. I offered Mr. Gessler the opportunity to describe what makes the Humboldt special; his response is unsummarizable. (I am well aware that is not a word, but it wasn’t.)

Thomas responded, “With Stern and Heisenberg, Audionet has attempted to redefine what is possible today in sound and music reproduction without regard to the effort and cost. It was to be another ‘Lighthouse’ project, with which we wanted to tear down the existing boundaries and redefine the sonic horizon. Thus, we spared no expense and effort and invested all our heart and soul. From conception to industrial design, circuit design, electronic components, and materials, we meticulously redesigned, tested, experimented, and validated everything. As a result, we have created pre- and power amplifiers that define the limits in terms of speed, stability, resolution, distortion, and noise, and in most cases are better than the competition by dimensions. Finally, audio does not sound like a machine any more—just pure, free, light, fine, delicate, and authoritative music and listening pleasure. How do you bring this all together in one housing? First of all, by making no compromises with regard to everything that is relevant to sound reproduction. It’s not the dimensions of a power supply, but its construction and its components that make the bigger difference. A smaller power supply will, of course, result in a loss of possible maximum performance. But this is something every customer has to decide for himself—what level of performance is required for him. By reducing the size of the power supplies, we gained a lot of space without any loss of sound quality. We were also able to reduce the size of the pre- and power amplifier boards because of the lower potential power requirements. But, also, without any noticeable loss of sound, because we did not abandon the decisive circuit details nor any components and materials relevant to sonic quality. Humboldt is, therefore, essentially a careful audiophile downscaling in the sense of potential absolute performance, without sacrificing the decisive sonic and technical merits of Stern and Heisenberg! If you want the absolute sonic and performance limit, choose Stern and Heisenberg; if you want the sonic and performance limit of an integrated amplifier, choose Humboldt. Like its big brothers, Humboldt sets the benchmarks of speed, stability, distortion, and noise for integrated amplifiers. And Humboldt also sounds like nothing: pure, free, light, fine, delicate, and authoritative music and listening pleasure. Actually, very simple, but technically, a Herculean task.”

Audionet Humboldt Integrated Amplifier Rear

The technical details, case design, inputs, and features were well explained in Greg’s review, and do not need to be reiterated as they are nearly identical, other than the obvious reduction in power supply, the single-chassis design, and the subsequent output-power reduction to 320Wpc into 8 ohms, 460Wpc into 4. For most, 320Wpc into 8 ohms is more than sufficient. For more power, look to the Stern/Heisenberg combo, and ye shall be satisfied. There are no DAC or phono modules available. As Bill Parish explained, “The concept of plug-in modules is simply not in conjunction with the level of performance the Humboldt has attained.” The Humboldt is built with the design principles of NASA, the resilience of a Sherman tank, the ease of use demanded by Apple, the aesthetic flair of a Manhattan plastic surgeon, and the engineering prowess of, well, a German engineer. Prächtige Skulptur!

Sonically, Humboldt resembles the atmosphere around Mount Everest. This integrated amp offers clarity, a complete absence of pollution, unrestricted vistas of majesty, the power and speed of an avalanche, and the romance, passion, and intensity of Into Thin Air. (See how I stuck with the Everest theme there?) The noise floor is also perceived like the “are they even there?” distant plains of Nepal as seen from Everest’s summit, 29,032 feet below. And like the wonder Everest is, the Humboldt’s presentation is natural in its truest form: smooth and mild-mannered when it needs to be, yet able to rage like Vesuvius. There is a variation and richness of timbre, which I perceived as simply better differentiated, with more palpable and clearer colors than most of what I have heard previously. Low-end extension is simply taut, unrestricted, and visceral without haze or savagery. Layering of the soundstage is on a completely different canvas, as if painted on a mountain wall as opposed to the confines of a typical canvas. The high-frequency reproduction is effortless, while never calling specific attention to itself. I found the midrange to be ever so slightly highlighted in the lower mids on some speakers, although this was imperceptible on others.

With the finesse of a French painter and the speed and handling of a McLaren 650s, the Humboldt is the fundamental expression of Thomas’ Lighthouse project. In essence, it takes what it is given, amplifies it, and sends it to the speakers without otherwise affecting the signal in any perceivable way. Imagine, if you will, watching water from a crystal-clear mountain spring silently fall off the edge of a great waterfall, plunging faster and faster. down thousands of feet to a cool blue lake below. The water is imbued with the energy that gravity exerts upon it; yet, the water itself remains completely pure, untouched, and unchanged. A “gravity amplifier,” as it were.

What the Humboldt offers is a bottomless noise floor that lets the music breathe, a sense of space, pace, and rhythm that would have been considered witchcraft in the late 1600s, because of the way it magically makes your body move and feel, and a sonic integrity and realism that just makes you laugh out loud. And all of this is in one box that looks like it was designed and built by NASA scientists partying with Frank Lloyd Wright. Considering that you avoid the price of interconnects, power cords, extra isolation systems, and a larger rack, the cost of entry is considerably lower than that of separates. Add a reference analog or digital source and a pair of well-matched top-tier speakers, and you can hop off the audiophile crazy train and settle in to enjoy the rhapsody of music without boundaries.

At some point in this parade of melodramatic hyperboles I’m supposed to say something on what I don’t like about the damn thing. Struggling to criticize, I could assign a hair too much body and artificially enhanced texture to the midrange. Also, the “lower power” of the amplifier didn’t grip low frequencies quite as well as a more powerful amplifier might, but only on speakers with lower sensitivity. When this happened, the texture and resolution of tympani and double basses were not quite as palpable and real as I have heard with absolute reference equipment. The density of timbre I mentioned before did, on very rare occasion, become oversaturated and a bit thick. There was a loss of the last micron of detail in hall presence, and vocal reproduction had a slightly thick layer about it. The realism of overall reproduction was a quarter-wavelength of a gamma ray away from perfection. All these phenomena occurred at an almost imperceptibly low level, but combined, they added up to a sound that intermittently exposed its electro-mechanical origin rather than one that instantly made you forget you were listening to anything other than music itself. Keep in mind that I’m desperately grasping at straws to find these “faults,” and these criticisms are only in comparison to the highest-resolution, best-performing, most insanely expensive amps and preamps I have ever heard. Omitting the standard reference to particular pieces of music that highlight this or that, I can comfortably say that changing a cable will affect the sonic integrity of the signal more than adding the Humboldt will.

How does the Humboldt compare to equally priced separates, and to other top-tier integrated amps. In the $55k price range, your options for very good amp/preamp combos are extensive, so a list of alternatives would be unrealistic. The abbreviated answer is that I think you would be hard pressed to find “better” at that price if you went to separates, which is an outrageous statement. Logic dictates that channel separation would have to be better with monoblocks, and that more power/damping on higher-output amplifiers would offer those obvious advantages to speakers that need them. The Humboldt’s channel separation and dynamics were meticulous and unconstrained, and I never felt as if I were missing what separates can offer in these regards, although I know the Heisenbergs unquestionably do those things better. The beauty of the Humboldt is, as mentioned above, the statement performance achieved while maintaining the simplicity of the integrated design, and the cost savings associated with reducing cables, isolation, racking, etc. The key to taking advantage of the Humboldt is properly matching it to the right speakers. When the Humboldt is mated correctly, the results are simply wondrous, and, believe me when I tell you, it doesn’t leave you wanting for more.

Forgive me if I exclude any others in the top-tier integrated category, but the Gryphon Diablo 300, Dartzeel CTH-8550 mk2, Constellation Argo, Ypsilon Phaethon, Vitus MP-I201 (significantly more expensive than the Humboldt) and SIA-030, Pilium Leonidas, Absolare Integrated SE, Soulution 530, CH Precision I1 are all world class. The mighty Vitus MP-I201 sits regally at around $120k and, sadly, I have never heard it, so I cannot comment on its performance or value. Price-wise, the Humboldt sits at the penultimate price position, with the others ranging from the mid-$20k’s to the high $40k’s. Sonically, the Humboldt offers pure neutrality, an insanely low noise floor, and supreme dynamic prowess, while conveying music with passion, soul, and energy. The other choices I listed are all damn good, and range in personality from warm and engulfing, to ultra-dynamic, to hyper-accurate and resolving. I’d put the $40k Leonidas and the $40k Vitus SIA-030 as the most comparable tonally. Your listening tastes, budget, and current equipment will help to define which direction you need to look in. As a reviewer, it’s not my job to tell you what’s better or worse, or what to buy. It is my job to tell you what the review subject sounds like, and what’s worth an audition, and if it’s something I would consider purchasing. Well, the Humboldt is unquestionably worth listening to and absolutely worth buying if you have the means. I was sad to see it go, and even sadder the following day when it was no longer in my room. Highly recommended.

Specs & Pricing

Output power: 320Wpc into 8 ohms, 460Wpc into 4 ohms
Frequency response: DC–700kHz -3dB
THD+N: <-100dB at 1kHz
SNR: >120dB (A-weighted)
Channel separation: >140dB, 20-20kHz
Dimensions: 450 x 320 x 505mm
Weight: 61kg
Price: $55,000