Tube Power Amp Reviews

Step 1: Find something that works. Step 2: Use it. Step 3: Repeat as necessary, then retire.

Everybody loves a bargain. No—make that: Most people love a bargain. Some just want the best, and they don't care about the cost. Some even distrust and reject out of hand any product that's not expensive enough. If you're one of these people, you might as well stop reading this review right now—the PrimaLuna ProLogue Three and ProLogue Seven are not for you. $1395 for a tube preamp? $2695 for a pair of 70Wpc tube monoblocks equipped with four KT88 tubes each? Must be based on old designs in the public domain using cheap parts carelessly assembled...

Single-ended triode (SET) amplifiers are typically paired with horn loudspeakers, for good reason: most SETs produce very low power, so to get acceptable loudness you need a highly sensitive speaker, which means horns. Similarly, horn owners are often advised that the best amplifier for their speakers is a SET. Certainly, the horn-SET combination can be magical, but, in my experience, SETs are not the only type of amplifier that can sound good with horns.

No one can say precisely how or when the ancient 300B triode tube made its cross-kingdom leap to the modern world of consumer audio, but we've got the where pretty much nailed down: It all began in Asia, where the best of the West is sometimes held in reverence rather than left to drown in consumerism's wake. Asia is the final resting place for the great Western Electric cinema systems of the 1940s—and that's where the 300B earned its un-American second act. By the mid-1990s, the tube had captured the hearts of hobbyists who, consciously or not, sensed that the audio refineries of the day had lost the plot, not to mention the body.

Two audiophile buddies of mine both own Rogue Audio M-150 monoblocks. I'd always been impressed with not only the sound quality of the M-150, but also its price. For $4495/pair, I thought my friends got a whole lotta amp for notta lotta dough. In this day and age, it's a rare and wonderful thing to get a pair of monoblocks, made in the US by a real audio company, that give you 150Wpc of tube power for under $5000. When Rogue came out with an update of the M-150, the M-180 ($5495), I thought it might be a good subject for my first full review in Stereophile. John Atkinson thought so too. I also thought it would be interesting to compare the M-180 with the very tube-like and almost identically priced Pass Labs XA30.5 two-channel amplifier ($5500), a sample of which I had on hand. (see my Follow-Up in August 2009).

When I began writing for Stereophile, I dreaded doing comparisons. They were stressful and tedious—and what if I got them wrong? But I quickly learned: Not only do readers enjoy comparisons, they need them. How else might they imagine the relative merits of the component under consideration? Once I realized this, I began acquiring a range of reference amplifiers.

But conspicuously missing from my audio menagerie has been a fast, neutral, 100Wpc tube amp to put more pop, fire, and maybe a little glow, into the Harbeth M30.2s.

Among the biggest buzzes at the January 2013 Consumer Electronics Show, and at Munich's High End Show the following May, was the sound in the room of Siltech BV, a Dutch company best known for its high-end cables. Siltech was demonstrating an innovative new power amplifier, and using it to drive the company's glass-cabineted Arabesque loudspeakers ($90,000/pair). The sound was unmistakably lush yet also remarkably linear, notably dynamic, and seemingly free of electronic artifacts. It sounded like the sound of "nothing"—which was really something!—and so much of a something that it caught the attention of many reviewers. But while there's often controversy and disagreement about a given product's sound quality, this time the enthusiasm seemed unanimous.