Rogue Audio Sphinx Tube Hybrid Integrated Amplifier

Class D With A Difference

Equipment report
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Integrated amplifiers
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Rogue Audio Sphinx
Rogue Audio Sphinx Tube Hybrid Integrated Amplifier

”Rogue” is one of those lovely, elastic words that give so much lyricism and color to the English language. Five hundred years ago a “rogue” would have been a low-level thief or beggar. And now? Well, Nissan certainly didn’t have that meaning in mind when it named its little crossover. Like many other words whose meanings have evolved over the years, “rogue” now could mean a slightly dishonest person, but more commonly someone who has a bit of a devilish (but not harmful) side. And there are those who may normally act under orders but then “go rogue” and do their own thing.

This last connotation is what Rogue’s owner and designer Mark O’Brien had in mind when he started the company 17 years ago, and all Rogue products reflect the moniker, especially in their refreshing design approach, price, and value. The Sphinx integrated amplifier, subject of this review, may be the most roguish of the lot. Tubes? One hundred watts per channel? U.S. design and manufacture? For $1300? Come on!

’Tis true. And nothing, as far as I can tell, is obviously traded away in build- and parts-quality. I’m still scratching my head over how Mark can do it. Throw in the facts that each and every Rogue component is hand-built or that Rogue calls Pennsylvania home and not Rick Perry’s business-friendly Texas—or China, for that matter—and the company seems all the more amazing. Like the bumblebee that the experts say should not be able to fly, perhaps Mark just doesn’t know any better. Or maybe he’s a bloody genius. After visiting Rogue’s facilities in Brodheadsville, I have to say my money’s on the latter.

Equally well known for affordable all-tube components, Rogue also offers a growing line of hybrid power and integrated amplifiers, which meld tubes and Class D outputs. The Sphinx is one of the latter. I’ve come to respect Class D for its efficiency but, thus far, cannot say it has equaled a good conventional transistor, much less all-tube, design in sonics. What Rogue has achieved, judging from the very affordable Sphinx, is not only demonstrably world-class sound, but the strongest argument I’ve yet come across for Class D topology.

Yes, the Sphinx is by nature energy-efficient, so I really was not surprised that it ran cool (barely warm to the touch even on the hottest summer days). More to the point for us audiophiles is that this is one ballsy amplifier. With 100 watts on tap into 8 ohms and 200 watts into half that impedance, this thing is powerful and can swing current. And with a damping factor of greater than 1000, woofers will love it. Damping factor is a specification which seems to have gone out of fashion over the years, but this doesn’t diminish its importance. In simplest terms, as the ratio of a connected speaker’s impedance to the amplifier’s output impedance, it’s an indication of control. The higher the damping factor, the more control the amplifier is projecting on the loudspeaker driver(s), especially the woofer(s). This control translates into bass accuracy and speed, sometimes described as “slam,” a quality which the Sphinx easily demonstrated in my auditioning.

Still, I get the sense that Mark O’Brien is not yet convinced that the perfectionist audio world is completely ready to speak of “Class D” in the same breath as “tubes” or “Class A”; the circuit topology used isn’t mentioned at all in the sales materials I’ve seen or in the owner’s manual. I sympathize, but this only reflects the less-than-fully realized promise of the circuit in the designs of others. In my experience Rogue is the first to bring Class D to a world-class performance level, but I think Mark knows he is going to have to do a lot of convincing.