as reviewed by Ed Kobesky

The most enjoyable system I've ever owned was also the simplest and least expensive. It consisted of an Onkyo CD player fed directly into a pair of Antique Sound Labs Wave DT SET amps. Those little 8-watt beauties powered my Polk RT25i monitors with surprising authority, and though the system was far from state of the art, it communicated the electricity of live music better than any I've owned since. Unfortunately, as I quickly discovered, tube gear can be finicky, especially on the budget end of the spectrum. The PrimaLuna ProLogue Two is the complete opposite. It could change everything for audiophiles who demand musicality and low maintenance. It's that important a product. Nearly every niggling problem associated with tubes has been effectively addressed, except for tube replacement, and even that has been rendered nearly hassle-free. Better still, the ProLogue Two made the hair on the back of my neck stand at attention every time I sat down to listen.

For most audiophiles, the scariest aspect of tube ownership is biasing. Tubes decay over time, and tube amp designers provide a bias adjustment to optimize current flow for the least distortion. Some amps have a built-in meter for this. With others, you need a DC voltmeter, and maybe a pair of rubber boots. You could rely on your dealer to bias your amp, but the current at his or her shop might be different than it is in your home. The ProLogue Two eliminates this concern by way of its proprietary Adaptive AutoBias circuitry. According to PrimaLuna's U.S. importer, Kevin Deal of Upscale Audio, this means no adjustments, ever. You don't have to use matched pairs of tubes, or even the same type. If a KT88 blows out, you can temporarily replace it with an EL34 if that's all you have on hand.

As with all tube amps, you'll need to replace the tubes every few years. Exactly how often depends on your listening habits. Some people get lucky, others don't. The good news is that if you can change a headlight on your car, you can retube a ProLogue Two. The tubes should cost between $100 and $200—not exactly trivial, given the fact that you can buy a very good integrated amp for that much. Then again, it won't be as unique as the ProLogue Two.

The only other special consideration regards cooling. Like all tube amps, the ProLogue Two needs open space on all sides, more space than a solid-state amp. If you can't give it at least four to six inches of space above and plenty around the sides, you'll want to put it on the top shelf of your rack or on a separate amp stand to avoid heat-related damage. Everything else you might worry about is handled internally, as the ProLogue Two hass a soft-start circuit to gradually bring the tubes on line, and an easy-to-replace fuse for protecting the output stage.

Obviously it's practical, but the ProLogue Two is also plenty sexy. Available with the buyer's choice of silver or black faceplates, it sports a high-gloss lacquer finish in "black sapphire" (actually a blue-black) and a build quality that's nothing short of stunning for the price. A pair of white gloves is provided so you don't smudge the finish—a classy touch. Kevin Deal triple-boxes every unit, and mine traveled from California to Pennsylvania without so much as a nick. There's no setup required aside from removing the foam tube protectors and plugging it in.

Kevin Deal insists that reviewers take the bottom off and have a look for themselves, and I was not about to resist. I saw point-to-point wiring—a nice touch, but not as uncommon as it used to be in budget gear. What is uncommon is the overall care of assembly and wire dressing. How they accomplish so much for so little money is no mystery—the ProLogue Two is assembled in China. For $1345, you even get a removable tube cage, which is generally an extra-cost option. It snaps on and off instantly. I left mine off because I couldn't bear to keep those gorgeous KT88 tubes all cooped up.

While the front of the ProLogue Two is the main attraction, the back looks pretty good as well, with a complement of beefy, gold-plated terminals you'd expect to find on a much more expensive product. If you're like me, you'll be giddy long before you tap the power switch.

Now comes the hard part, which is describing the sound of the ProLogue Two. Should I compare it to similarly-priced tube gear? I could, but much of its competition aims for a purposely soft, romantic sound that is initially appealing but unsatisfying in the long run. I could compare it to solid-state integrated amps I've owned in its price category, but they all seemed to shoot for maximum slam and detail. I decided to throw all comparisons aside and simply tell you what I heard.

The first thing I noticed was a unique sense of air and aliveness. Even before Keith Jarrett played his first note on side one, record one of the monolithic 10-LP box set, Sun Bear Sessions (ECM 1100 ), there was more atmosphere than I'd ever heard. It was downright eerie, and for some listeners, it could be revelatory. Get ready, analog fans: LP + KT88 = a synergy that's not to be believed.

When the music started, the ProLogue Two surprised—no, shocked—me by painting a smooth sonic picture that was also controlled and coherent. Many tube amps I've heard are slow in the midrange, dull on top, and loosey-goosey on the bottom. Not the ProLogue Two. It can't compete with solid-state amps in terms of tightness and fastness, but it never sacrifices detail to provide a warm, soothing presentation. It just sounds good, and not in a deliberately tube-like way. Music is presented in its entirety. At moderate to medium-high volumes, it does a remarkable job of sorting out instrumental lines, right down to the individual notes. I'd have no qualms about pairing it with sources and speakers that cost many times its absurdly low price. It also brought out the very best in budget gear. Whether fed the signal from my NAD C521i CD player or a $50 Sony CD Walkman, the results were musical. The ProLogue Two can be alternately forgiving and revealing. That, in a word, is magic.

The ProLogue Two never put a foot wrong. It's the first amp I've heard in a long time that could bang out bass-laden hip hop tracks, as on The Streets' CD Original Pirate Material (Atlantic 93181), then turn on a dime and resolve the fragile shadings of a minimally-backed female vocalist like Holly Cole on her Tom Waits tribute record, Temptation (Metro Blue 8316532). It was human, expressive, and open sounding to a fault. The only way you'd outgrow this amp is if you upgraded to speakers the size of a Kia, and even then, the ProLogue Two could probably power them to a reasonable volume.

There's another reason to consider the ProLogue Two. If you don't like the sound of your solid-state amp, you're pretty much stuck unless you're willing to risk going in with a soldering iron to replace resistors and capacitors. Even then, the benefits are usually subtle. Not so with tubes. You can have a blast trying different tubes until you get precisely the sound you want. It's a relatively cheap way to stave off an acute case of upgrade-itis.

The PrimaLuna ProLogue Two may not be as energetic as a solid-state amp, nor will it exert the same level of control. That, however, is the key to its appeal. Music flows through it gracefully. What comes out is lush but not slushy, alive but not prickly, and involving as all get out. The PrimaLuna ProLogue Two garners my strongest recommendation. It's not merely a great tube amp, but a great amp, period. Ed Kobesky

ProLogue Two
Retail: $1345

Upscale Audio
web address: www.upscaleaudio.com

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