Mark Levinson No.333 power amplifier

If I've read it once in mainstream audio magazines, I've read it a hundred times: "The most important component in a system is the loudspeaker, because it is the loudspeaker that makes the sound." Putting aside the obvious illogic of this statement—that without other components in the playback chain, even the perfect loudspeaker can't make a sound—my experience is that it just is not so. Yes, it is true that changing from one loudspeaker to another makes the greatest overt changes in a system's sound. Yet I have found that it is the source components—and, even more, the amplifier—that most affect a system's ability to make music, as opposed to sound. Pass the signal from a great front-end through a poor amplifier on its way to great loudspeakers and you end up with amusical dreck. By contrast, feed a great source to a great amplifier, and you can coax great music from quite unpretentious speakers.

Which is how it has been in the Atkinson listening room for almost 20 years. Whatever speakers I have chosen to use, at whatever price level, they have been driven by the best amplifiers I could lay my hands on. And from 1987 through 1995, that was the pair of Stereophile-owned Mark Levinson No.20.6 Reference monoblocks. Even when I was reviewing inexpensive minimonitors, the monstrous class-A Levinsons, with their fully regulated output-stage power supplies, squeezed the maximum musicality from them. Other audiophiles apparently agreed with me: During the product's 10-year lifetime, in its No.20, No.20.5, and No.20.6 incarnations, Madrigal Audio Laboratories sold over 7500 of them (and about 10,000 of the dual-mono designs based on it, the Nos.23, 27, and 29).

But in 1995, following the introduction of their Mark Levinson No.33 Reference monoblock, Madrigal launched a series of dual-mono designs based on that cost-no-object tower: the 100Wpc No.331 ($4550, positively reviewed by Larry Greenhill in the January 1996 Stereophile, Vol.19 No.1); the 200Wpc No.332 ($6495); and the subject of this review, the $8495, 300Wpc No.333.

Other than the fact that the No.331 is 1" shorter than the other two, the three Levinson '33X amplifiers are identical-looking. Only its 146-lb mass gives the No.333 away—this is one dense block of a two-channel amplifier. Specified as being a voltage source, it offers 300Wpc into 8 ohms, doubling that into 4 ohms, and doubling it again into 2 ohms. Input connectors are a pair of RCA jacks paralleled by XLRs (wired with pin 2 hot). Two pairs of 100A-rated, insulated loudspeaker connectors are provided for each channel; these are Madrigal's winged types, which accept spade lugs or bare wires but not bananas. While the No.331 has a detachable AC cable, the No.333, which can draw over 45A from a 120V AC line at full power when driving a 2 ohm load, has a nondetachable cord. There is also a "Comms" input, allowing the amplifier to be switched in and out of Standby mode by a Levinson No.38 or '38S preamp.

It isn't possible in the space available to examine the No.333's technology in the depth it deserves. However, like the other '33X-series designs, the No.333 features: dual-mono design with completely independent power supplies; two shielded toroidal transformers, one for each channel, oriented to cancel stray magnetic fields; "wire-free," bus-bar–based circuit layout to minimize parasitic effects; balanced signal circuitry based on the No.33 Reference amplifier; a soft-clipping circuit to reduce the subjective effects of amplifier overload and clipping; full overload protection; Motorola bipolar output devices; and three voltage-gain stages with regulated supplies (these supply wider bandwidth and lower source impedance than those in the '331).

The output stage has unregulated supplies, but more important, the output stage has what Madrigal terms "Adaptive Biasing," whereby the standing bias current is small at low output power and large at high powers, smoothly changing in between. The benefit of this is to endow the '333 with much of the sonic benefits of class-A output-stage operation without the heat penalty.

All in all, the No.333 is a smart-looking, beautifully constructed dual-mono amplifier.

First the bad news, or what passes for it. In level-matched comparisons with the pair of No.20.6es, the No.333 had slightly less bass impact. Whereas the 100Wpc monoblocks, which retailed for almost twice the price as the No.333, with their regulated output-stage voltage rails, had low-frequency slam that slapped you in the face, picked you up, threw you against the wall, dusted you down, then set you back in your seat, the 300Wpc '333 had "merely" excellent bass. Yes, it was deep; yes, it was powerful; yes, without reference to the monoblocks, it was all I would want. But there has to be a reason for Madrigal to make the $32,000/pair No.33, I guess.

The good news is that the No.333 lacks the slight upper-midrange grain that is the decade-older amplifier's weakness. In fact, the '333's mids and highs sounded smooth, smooth, smooth, with an excellent sense of air and space. There was a refreshing freedom from the cold, analytical character that to me is typical of solid-state amplifiers and that many audiophiles mistake for "accuracy." No matter what loudspeakers I used with the Levinson—and I used a lot—there was never any feeling that the amplifier was imposing its own signature on the sound. You could say that the dynamic range of the differences between the sounds of the loudspeakers was as wide as it possibly could be, a tribute to this amplifier as a reviewing tool. But when the listening for work was over and the listening for pleasure began, the '333 proved an excellent fatigue-free conduit to the music.

An area where the No.333 excelled was dynamics. I never got the sense that I was running out of headroom, even on high-level, percussion-heavy recordings. Yet, perhaps more important for a high-power amplifier, the Levinson remained transparent at very low levels. Often, the designer's need to use multiple pairs of transistors to obtain the combination of high output voltage and output current results in a murkiness at low levels. This wasn't the case with this amplifier: in the performance of the Brahms Horn Trio on Stereophile's Serenade CD, there is a magical moment when horn soloist Julie Landsman (first chair of the Metropolitan Opera Orchestra) and violinist Sheryl Staples (associate concertmaster at Cleveland) are playing the slow movement's theme triple-pianissimo. When I made the recording at the 1995 Santa Fe Chamber Music Festival, I tried to capture the full dynamic range of the live sound, which meant that this elegiac passage peaks at no more than –50dBFS. Yet with the Levinson driving the B&W Silver Signaturess, you could easily hear the slight unevenness in the violin tone that results from the player not using vibrato and drawing the bow very slowly across the string. This is one transparent amplifier.

The Levinson's soundstaging was excellent, but I must admit that I've heard better. Not from solid-state, it must be added, but when I compared the No.333 with the single-ended Cary 300SEI, for example, matching the levels at 1kHz, there was no doubt that the tube amplifier gave a more palpable sense of musicians actually being in the room. That was only true, however, as long as the music stayed reasonably quiet. Once things got loud, the little Cary crapped out in a hurry. And taken as an overall performance package, the Levinson did more of what I need, more consistently, more of the time.

Summing up, the overall system sound with the Levinson in the chain was consistently lush, spacious, detailed, and effortless—a tribute to the quality of the amplifier.

Summing up
While it doesn't have quite the low-frequency solidity of the No.20.6 monoblocks that it replaced in my system, the powerhouse Mark Levinson No.333 has a more natural-sounding midrange and grainfree treble, and throws a spacious, well-defined soundstage. Its lush yet forceful presentation got the best from all the speakers I used it with. This is a solid-state amplifier you needn't apologize for to your tube-owning friends.

By rights, no amplifier costing as much as the average Stereophile reader's entire system could be called a bargain. But at $8495 the Mark Levinson No.333 is significantly less expensive than the pair of No.20.6es it replaced in my system. More important, it is, overall, the best-sounding amplifier I have yet heard from Madrigal. And that qualifies it as a bargain.

Mark Levinson, Harman Luxury Audio Group
8500 Balboa Boulevard
Northridge, CA 91329
(888) 691-4171

Bogolu Haranath's picture

Another great amplifier from the 90's :-) .........

CG's picture


I wonder what the closed loop phase margin is.

mtrot's picture

Hmm, I wonder how this would compare to my Krell FPB 400cx from back around that same time period? Even with its 400 wpc power rating, it doesn't seem like it has all that much bass impact.

a.wayne's picture

Best Krell for bass were the early KSA 100 Mk2’s ..


a.wayne's picture

With that much ringing i would’nt touch it , very unstable IMO ...