Mark Levinson ML-2 monoblocks
The little-known and underrated Hadley Laboratories 622C aside, this was the first solid-state amp I heard to put the transistor on an equal footing with the tube. Introduced in 1977, these 25W Class A monoblocks (50W into 4 ohms, 100W into 2 ohms) from Mark Levinson set a new standard of clarity, liquidity, timbral beauty, and three-dimensional imaging and soundstaging for solid-state. The polar opposite of the grainy, piercing, high-in-odd-order-harmonics sound that many of us then associated with solid-state designs, the ML-2 proved that the transistor could make music as readily as it could generate power.
Krell KSA-50 monoblock
Dan D’Agostino’s dark, delicious, 50W Class A monoblock from the early 80s brought something to the table that we hadn’t gotten in quite the same way before: bass! Along with enough current to drive impossible loads like Apogee ribbons or Sound Lab ’stats. One of the truly great, pioneering solid-state designs, the KSA-50 was perhaps the first solid-state amp that could be justly called unflappable.
Conrad-Johnson Premier Four
It may seem capricious to bypass earlier c-j products, including its classic 55W MV60 stereo unit (which ushered the phrase “palpable presence” into the audiophile vocabulary) and the higher-powered and more highly regarded Premier One, for this relatively little-known 100-watter introduced in 1983, but I’m a sucker for EL34-based amps and this one was, IMO, the best of all time—astonishing soundstaging and imaging and an overall realism of tone color and texture that has rarely been equaled in a pentode tube amplifier. Anyway you slice it, a conrad-johnson Premier amp belongs on this list (or, at least, my list).
Lamm Industries ML-2 monoblock
Throughout the SET craze of the mid-to-late 90s, I listened to a lot of single-ended-triode amps from Japan, Great Britain, and the U.S. None was (or is) as natural as Vladimir Lamm’s 17Wpc masterpiece, the ML-2. This was the first and virtually only SET amp I heard that didn’t sacrifice bandwidth or low distortion or a neutral tonal balance to achieve that sonic “directness” that only SETs then seemed capable of. Though it has recently been replaced by the ML-2.2, which judging by its showing at this year’s CES is even better, the ML-2 was for more than a decade not just the best SET but the best low-powered amp on the market.
Audio Research Corporation Reference 610T monoblocks
The culmination of William Zane Johnson’s glorious career as an amplifier designer, the 600W+ 610T is the best ultra-high-powered pentode tube amplifier JV has yet heard—a paragon of neutrality, resolution, transparency, bloom, dimensionality, and seemingly limitless power from the bass to the treble. You can argue about the virtues of solid-state bass and treble vis-à-vis tube bass and treble, but what you can’t argue about is the overall realism of this amp’s sound. Since the 610T is also, in all probability, the last WZJ tube amp we will see, it makes a worthy final statement from one of high-end audio’s true greats—and final chapter to the high-end’s Golden Age.
Technical Brain TBP-Zero monoblock
Along with the Soulution 700, this 350W Japanese monoblock from designer Naoto Kurosawa is a poster-child for the New Age in high-resolution, low-distortion solid-state amplification that, for some of us, has wiped away any lingering prejudices we’ve had toward the transistor. Reviewed in this issue, the TBP-Zeros—which forgo the use of those banes of transitor amps, the emitter resistor—are simply the highest resolution, highest transparency-to-sources audio components I’ve yet auditioned, tube or solid-state. Though not all listeners will welcome this level of neutrality—which, while never punishingly analytical, does not do poor recordings the favors that more euphoniously colored tube and solid-state amps do—to me Technical Brain sets a new standard in high-fidelity reproduction that is currently challenged only by the slightly more gemültich Soulution 700 monos.
This is a legendary amplifier, and from a legendary company, whose commitment to quality of construction and design has never wavered, not even during its long dark night of solid-state electronics. The earliest Mc’s were built around the transformer that Frank McIntosh and Gordon Gow designed (and patented), one that allowed them to move beyond the power limitations of Class A design and into the region of much higher outputs, without the audible and ugly “notch” distortion that had thwarted such efforts in the past. Historically important. The 275 has been restored as the company in the past several years has finally moved back into tubed amplification production, and with stunning results (I think its 300/300 watt 2301 unit is the purest sounding amplifier in my experience—to date.)