Solid State Power Amp Reviews

When I reviewed it back in April 2003, I found the Lamm M2.1 hybrid monoblock amplifier to be one of the most thoroughly convincing and lifelike components I had ever heard. Just last month, I concluded that its revised, less powerful sibling, the M1.2 Reference, just might be the finest overall amplifier to be heard anywhere. Though the owner's manual doesn't go into details, I believe it safe to assume that the revisions embodied in the M2.2 are similar in extent to those that resulted in the M1.2. Which inevitably led me to ask: What is the exact difference between the $19,990/pair M1.2 Reference and the $19,390/pair M2.2?

The Lamms can be contrasted in two principal parameters: total output power and output stage bias. The M1.2 Reference delivers its 110W into 8 ohms in pure class-A mode, while the M2.2 is rated at double the power—220W into 8 ohms—but runs up only to 41W in class-A; thereafter, it operates in class-AB up to its rated power. Like the M1.2, the M2.2 is a hybrid design with a solid-state input stage, a single 6922 tube as the driver, and a MOSFET output stage. The M2.2 can be configured via its rear-mounted bias switch to deliver as much as 900W into 1 ohm. (Art Dudley and I have recently gone on at length about the underlying philosophy and quality of Vladimir Lamm's designs, so I won't repeat those musings here. See his review of the ML2.1 in the October 2004 Stereophile, and my review of the M1.2 Reference in the February 2005 issue.)

My evaluative listening was done with my regular analog rig of the SOTA Cosmos Series III turntable, Graham 2.2 tonearm, Dynavector XV-1S moving-coil cartridge, and Manley Steelhead phono preamp, as well as with a Classé Omega SACD/CD player, VTL TL-7.5 Reference line stage, and, mostly, Legacy Whisper speakers (under review). Tetra's 505 LTD speakers put in a brief appearance at the end of the audition period. The wiring was Cardas Golden Reference speaker cables and Harmonic Technology CyberLight interconnects, with Shunyata Hydra AC conditioning and cords. I'll have much more to say about the CyberLights soon.

The Lamm M2.2 represented a small but, at these levels of performance, significant advance in virtually every aspect of sonic performance over the M2.1, at least as I remember the earlier amplifier. The residual darkness in the top octave that characterized earlier Lamm amps has been largely mitigated in the M2.2 and M1.2 Reference. Aural memory being fleeting and imperfect, it sounded to me as if the M2.2 had just a bit more lifelike sparkle in the treble. The M2.2 sounded nearly identical to the M1.2 Reference about 90% of the time, which is not surprising—the amps' circuits are essentially identical, and the upgrades from .1 to .2 status are the same in both amps. It was the 10% of the time that I heard differences that showed how small variations can matter.

When I listened at medium and higher levels, especially to vocalists, the M1.2 had more touchability and, if you will, living presence. Not that the M2.2 fell short in this respect—it was on the same level as such benchmark amps as the Atma-Sphere MA-2 Mk.III. But the M1.2 Reference is the finest I've heard in that area of performance. Conversely, the M2.2 had an even greater sense of dynamic openness at really loud moments. This is a meaningful statement, given that the M1.2 is the biggest-sounding 100W amplifier I have heard. The difference, I suspect, is that the M1.2 Reference is a pure class-A design. While the M2.2 is biased heavily to class-A, that it is not pure class-A may well logically account for both the M1.2's extra bit of delicacy and palpability and the M2.2's even less restrained dynamics.

So, given the small difference in price, why shouldn't the prospective Lamm owner spend the extra $600/pair and pop for the M1.2 Reference? The M2.2 and the M1.2 Reference both sound marvelously true to life, both run hot, and both are superbly built yet easy to manage and live with. The answer is simple: Some speakers need the sheer might offered by the M2.2. If you own big planars or are playing big box speakers of only moderate efficiency in a large room, twice the power should definitely factor into your considerations. The extra whomp that the M2.2 offers will be necessary in a lot of systems. Not that you'll give up very much if you choose the M1.2 Reference, or will even give it up very often—there's no such thing as a "second best" from Lamm. This is a no-lose choice.—Paul Bolin