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Lamm ML2.2 Single-Ended Triode Amplifier

The highest praise I can give the Lamm ML2.2 is that it doesn’t sound like a single-ended-triode amplifier. That may seem like an odd way to start what you’ll soon see is a rave review of an SET amp, but it reflects the fact that the ML2.2 is far more than just another low-powered SET. In fact, it is singular in its ability to deliver SET virtues while minimizing their limitations.

The ML2.2 is the latest upgraded and refined version of Lamm’s famous ML2 introduced in 1998, and the ML2.1 launched in 2004. This latest iteration benefits from having been designed after Lamm’s groundbreaking ML3 Signature, a $139k four-chassis 30W SET whose sound (when driving the right loudspeaker) can only be described as magical. The new ML2.2 features design elements Vladimir Lamm developed for that reference amplifier, including a new input stage that is similar to that of the ML3. Compared with the ML2.1, the ML2.2 also offers an entirely new power transformer, five filter chokes in the power supply (versus two chokes in the ML2.1), and a new, better-sounding circuit-board material.

The ML2.2 is solidly built but decidedly utilitarian in appearance. This is a serious piece of audio engineering, not living-room jewelry. The black chassis houses the power and output transformers at the rear, with the tube complement at the front. Those tubes include a 12AX7 in the input stage, 6N6Ps as the drivers, and a 6C33C output tube to deliver 18W of output power. A second 6C33C serves as the series-pass element in the fully regulated output-stage power supply. (A 6AK5 and 5651 are also part of the power supply.)

The power transformer has no direct mechanical contact with the chassis or covers; it is instead suspended in a vibration-absorbing encapsulating material. The output transformer (a critical component in any tubed amplifier, particularly an SET) is a custom, hand-wound design with a very low turnsratio, designed specifically for the 6C33C output tube. This transformer has three taps that correspond to the three output terminals, allowing you to select the one that best matches your loudspeaker’s impedance. The power supply includes a soft-start circuit that slowly ramps up the plate voltage to extend tube life. It takes about two minutes after turning on the amplifier for the front-panel red light to stop blinking and glow solid red, indicating the amplifier is operational. A pair of test points and trimmers on the top panel allows the user to correctly set the plate voltage and plate current. (You’ll need an accurate voltmeter along with the supplied screwdriver to perform these tasks.)

I’ve had the ML2.2s for some time but have been waiting to write about them until I mated them with a loudspeaker of appropriate sensitivity and impedance characteristics for their 18W of output power. Ideally, the ML2.2 will drive a loudspeaker with a sensitivity of at least 94dB, one that has a fairly flat impedance magnitude across the audio band and no severe swings in its phase angle (that is, a speaker whose impedance is more resistive than reactive). I found that speaker in the Magico Q7, reviewed in the previous issue. With a sensitivity of 94dB and what is apparently a benign impedance, the Q7 allowed me to hear the ML2.2 at its best. The Q7’s extreme resolution and transparency also provided a clear window on the ML2.2. Incidentally, other loudspeakers with similar sensitivities (the 93dB Venture Ultimate Reference and 94dB Lansche No.7) didn’t fare nearly as well with the ML2.2. This isn’t casting aspersions on these two loudspeakers. Rather, it just happens that they are more difficult to drive than the Q7 despite their similar sensitivities. There’s no substitute for auditioning the amplifier/loudspeaker pair before making a purchasing decision, particularly where lowpower SETs are involved.

I started this review by stating that the ML2.2 doesn’t sound like an SET. If I brought an experienced listener into my room blindfolded and played a wide range of music for a couple hours, that listener would never be able to identify the amplification as single-ended triode. For starters, the ML2.2 has an absolutely luscious rendering of tone color, yet it never crosses the line into a syrupy romanticism that would soon grow tiresome. The amplifier lacks the typical SET signature of an overly warm and ripe midband that directs the musical focus to certain instruments. And then there’s the bass, the Achilles’ Heel of SET. The ML2.2’s bottom-end extension, control, dynamics, and articulation wouldn’t be mistaken for a solid-state dreadnought design, but neither would you think that this 18W SET could deliver the kind of bass control and dynamic drive it exhibited driving the Magico Q7.

The ML2.2 is so natural, organic, and musically right—and so greatly minimizes an SET’s traditional shortcomings—that the amplifier caused me to question the modern paradigm of highpowered solid-state amplification (see my editorial “The Single-Ended Triode Paradox” in Issue 223). Have the last fifty years of amplifier design been a detour down the wrong path? Listen to, say, the new Analogue Productions 45rpm reissue of Time Out by The Dave Brubeck Quartet through the ML2.2 and you’ll be asking that question as well, no matter what your technical persuasion. Joe Morello’s ride cymbal just hangs in space with startling realism that makes it sound like it was recorded yesterday; Paul Desmond’s alto glows with a gorgeous liquidity and richness of tone color; and Brubeck’s intricate piano lines between the melody phrases on “Blue Rondo à la Turk” are conveyed with a newfound clarity that deepened my appreciation of this brilliant composition and performance. I defy even the most hardened anti-SET technocrat to listen to the ML2.2 driving the Q7 and conclude that a vacuum tube amplifier with 18W of output power at 3% THD is an anachronism and an abomination. And the argument that SETs sound good because of their high harmonic distortion rather than in spite of it simply doesn’t wash under careful listening. The ML2.2 sounds like whatever the source sounds like, with no common editorial signature from recording to recording.

What makes the ML2.2 different from other amplifiers— tubed or solid-state, single-ended or push-pull—is a sense of palpable realism and the feeling that music is being brought to life contemporaneously. The ML2.2 doesn’t sound like just a great tubed amplifier, only a little better; it provides a fundamentally different listening experience. This amplifier’s sound is qualitatively superior, not quantitatively. As I discussed in my review last issue of the Q7, realism is the ultimate goal of high-end audio, and therefore the ultimate reference standard for judging audio products. And realism is what the ML2.2 delivers, in spades. Instruments and voices sound realistic in timbre, in dynamic shading and expression, in their spatial presentations, and in the joyous feeling of people creating music before you.


The ML2.2 sounds so real in part because of a few specific qualities that can be identified and described, but also by qualities that are ineffable. The specific qualities include, first and foremost, grain-free, ultra-liquid, and deeply saturated tone colors. The brass and woodwinds on 88 Basie Street [JVC XRCD], for example, just sounded that much closer to the sounds of those instruments in life. Listening to the ML2.2 pointed out to me that even the great amplifiers overlay instrumental textures with a slightly synthetic tincture that hardens the timbre and reduces the sense of ease and involvement. The ML2.2 is utterly natural, organic, and free from any hint of electronic haze. Significantly, the ML2.2’s liquidity and ease aren’t the result of softening the treble, slightly reducing resolution or rounding transient information. In fact, this amplifier has a full measure of treble energy, is ultra-high in resolution, and has whip-fast transient performance. The difference is that the ML2.2 doesn’t make the treble sound as though it’s a separate component of the spectrum. Neither does it artificially hype detail or add etch to transient leading edges. It simply presents music in a way that sounds closer to the way live instruments sound, and less like a hi-fi recreation of them.

Another of the ML2.2’s strengths is its ability to make crystalclear subtle musical lines that, through other amplifiers, become part of a homogenized background. The ML2.2 allowed me to hear, without effort, what every musician is doing at any time. Countless times I found myself discovering nuances of expression in “background” parts that turned out to be essential to the piece’s presentation. This quality is in part aided by another of the ML2.2’s great attributes, the impression that the instrument exists in tangible space, not in a freeze-dried vacuum. I could hear a halo of air around the image, and that halo expand outward with its dynamic envelope, a quality for which Jonathan Valin coined the term “action.” Not only that, but the ML2.2 portrayed the reverberation around the instrument with a density and complexity that one hears in life. The decay surrounding the piano of Nojima Plays Liszt on Reference Recordings was richly portrayed, and with it came a heightened impression of a piano in a hall, “lighting up” the acoustic. When these qualities are combined simultaneously as they are in the ML2.2, the result is an extremely powerful connection with the musical expression.

When driving the Q7, the ML2.2 was my amplifier of choice with about 75% of my music collection. With the other 25% I would sacrifice the ML2.2’s unique qualities for greater bass extension and control, wider dynamics, and the ability to reproduce musical climaxes without strain. If you want to hear the Q7’s spectacular bass extension, bottom-end power and drive, and bass impact, the ML2.2 probably isn’t the amplifier for you. The ML2.2 won’t reproduce orchestral climaxes with the same authority and lack of strain as a big solid-state amplifier. It also fails to fully convey the powerful rhythmic drive of rock, blues, and some jazz. My 75%-to-25% ratio will vary from listener to listener depending on musical taste. If your proclivities lean toward chamber music, acoustic jazz, and vocals, the ML2.2 will likely be perfectly suited to 100% of your collection. And keep in mind that the higher the loudspeaker’s sensitivity, and the more benign its impedance, the less the ML2.2 will be limited in bass and dynamics. With a loudspeaker of 98dB sensitivity and a flat impedance magnitude and phase angle, the ML2.2 will sound like a powerhouse. Nonetheless, I must reiterate that it would be a mistake to think of the ML2.2 as just another SET amplifier with all of that technology’s limitations in the bass. No other SET I’ve heard has the ML2.2’s control, dynamics, and authority in the bottom octaves.


The Lamm ML2.2 surely belongs in the pantheon of the world’s greatest amplifiers—of any price or technology. This amplifier delivers the kind of special listening experience that you must hear for yourself to understand just how special it is—and how it can make other amplifiers, even the most highly regarded tube and solid-state designs, sound somewhat flat and sterile by comparison.

As I thought back on my listening experience to write this description of the ML2.2’s sound, I found that the memory of the listening sessions with the Lamm was more vividly etched in my mind than listening sessions with other amplifiers. Recalling specific pieces of music, I relived the sense of musical discovery, of communication from artist to listener, that is the hallmark experience of living with this special product.

As great an amplifier as the ML2.2 is, it’s not for everyone or for every loudspeaker. You must match it with an appropriate loudspeaker and be aware that it won’t deliver the bass extension, control, and dynamics of less expensive solid-state designs. You must also be prepared to make front-panel adjustments using a voltmeter, as well as to replace tubes periodically.

But the caveats end there; in every other respect—and I mean every respect—the Lamm ML2.2 is stunningly great. Once you hear the ML2.2 under the right conditions, your world will be forever changed. I know that mine has been.


Type: Single-ended triode monoblock power amplifier
Power output: 18W continuous into 4, 8, or 16 ohms at 3% THD
Tube complement: 12AX7, 6N6P (x2), 6C33C (x2), 6AK5, 5651
Frequency response: 20Hz–20kHz (–0.3dB) at 18W into 16 ohms
Signal-to-noise ratio: 90dB A-weighted at 4V into 16 ohms
Inputs: Pseudo-balanced on XLR jacks, unbalanced on RCA jacks
Output taps: 4, 8, 16 ohms
Input impedance: 41k ohms
Output impedance: 0.84 ohms, 30Hz–20kHz (8-ohm tap)
Damping factor: 9.5 at 1kHz
Power consumption: 245W at rated output
Dimensions: 16″ x 8.25″ x 20.375″
Weight: 81 lbs. each (net)
Price: $37,290 per pair

Lamm Industries , Inc.
2513 E. 21st Street
Brooklyn, NY 11235
(718) 368-0181

Associated Components

Digital Sources: dCS Vivaldi system (transport, upsampler, clock, DAC); Berkeley Audio Design Alpha DAC Series 2; iMac server with Berkeley Alpha USB interface, MacBook Pro; Pure Music and Audivana playback software
Analog Source: Basis Inspiration turntable with Basis Vector 4 tonearm, Air Tight PC-1 Supreme cartridge; Simaudio Moon 810LP phonostage
Preamplifiers: Rowland Corus, Constellation Perseus
AC Conditioning and Cords: Shunyata Triton and Talos, Audience aR6TS conditioners; Shunyata Zitron Anaconda and Audience Au24 AC cords
Cables: Shunyata Anaconda interconnects and loudspeaker cables; MIT MA-X2 and MA-C interconnects, MIT MA-X SHD loudspeaker cables; AudioQuest WEL Signature interconnects, Transparent XL Reference interconnects; AudioQuest Diamond USB WireWorld Platinum Starlight USB
Equipment Racks: Stillpoints Isolation: Stillpoints Ultra SS and Ultra5
Acoustics: ASC 16″ Full-Round Tube Traps, 10″ Tower Traps
Accessories: VPI 16.5 recordcleaning machine; Mobile Fidelity record brush, cleaning fluid, stylus cleaner


By Robert Harley

My older brother Stephen introduced me to music when I was about 12 years old. Stephen was a prodigious musical talent (he went on to get a degree in Composition) who generously shared his records and passion for music with his little brother.

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