Rogue Audio Sphinx integrated amplifier

Stereophile 07/2014

Herb Reichert 

Once, on a cold, dank, soundless day deep in the Eastern bloc, I watched a man spend over a million dollars on an audio system: a turntable, a fancy horn tweeter, a few wires, and some amplification for his modified Klipschorns. I asked him what he did for a living, and he told me he was a notary public.
Everyone there smirked and watched as he excitedly put the tonearm down on the first record, AC/DC's Back in Black. He laughed, he danced, he didn't sit down. He just skipped around the room, grinning and bouncing like a caffeinated child.

I thought, Does this man really need all this expensive gear to get that bouncy?

That notary public came to mind while I was removing my venerable Creek 4330 integrated amplifier and hooking up the new Rogue Audio Sphinx. As I connected the speaker cables, I could hear Music Hall's Roy Hall admonishing me, "You don't need no million-dollar hi-fis—just get you a little integrated and some good British two-way speakers."

The Sphinx costs almost 700 times less ($1295) than the amplification in that million-dollar system. It's a class-D (switching) amplifier, with a linear (not switching) power supply, that outputs 100Wpc into 8 ohms or 200Wpc into 4 ohms. It has a high-quality Avel Lindberg power transformer, a 12AU7 tubed line stage with three inputs, a phono stage with 40dB of gain, a fixed output (for a separate headphone amp or recording), and a variable buffered output (for driving a subwoofer or a second amp). It also has a balance control, an optional remote volume control ($100), and a discrete headphone amplifier with a front-panel jack. It's all contained in a solid-feeling but conventional-looking case that weighs 25 lbs. And, surprise surprise, this unassuming, solid, no-bling product is made in Brodheadsville, Pennsylvania, and is surely about 162 times more user-friendly and long-term purchase-wise than that boxes-full-of-Franklins stuff I mentioned at the start.

Just before the Sphinx arrived, I was lost in a mad and unusually deep exploration of solo-piano music and what I erroneously call High French Modernism. Mainly, I was playing records of compositions by Debussy, Ravel, and Satie, alternating with soulful cabaret music by Édith Piaf, Serge Gainsbourg, and Daft Punk.

I stream a lot of music, listening in the background as I do my workaholic thing. But this whole Paris groove had me retiring early, turning down the lights, lying on the couch, and dreaming my way into the music. I wasn't just listening and relaxing; I had an agenda: As I searched one record after another, I was trying to hear more of what these French composers were really about. Often, in the middle of a piece, I'd jump up and grab a book on music or go online to look up something. I was playing records to discover a time and a place that I could never visit. I wanted these records to take me to the cabarets and concert halls of Paris during La Belle époque. So it was natural that I feared this modestly priced integrated might throw some flat Moët and stale Gauloises into my nightly excursions to Montmartre.

Switching Moods

But before I begin telling you how the Sphinx played this music, I feel compelled (though not fully qualified) to discuss the "class-D amplifier" aspect of its design. My 1974 edition of Howard M. Tremaine's Audio Cyclopedia (Howard W. Sams & Co., New York) says that the term class-D was first proposed by the revered Norman Crowhurst, to classify a pulsed-type transistor audio amplifier that could be operated at something close to 100% efficiency by continually switching between the power supply rails at an ultrasonic frequency. My weirdo audio-designer buddies consider anything less than pure class-A (in which the audio signal current is never completely turned off) a cost-cutting compromise aimed at middle-level consumers, and definitely insufficient for perfectionist audio. While class-A amplifiers can easily sound beautiful—and glowing and colorful and textured—they are also very inefficient at converting 120V wall power into properly scaled current to drive loudspeakers. They require big power transformers and storage capacitors. They generate lots of heat and cost lots of dollars per watt to make and use. Class-D is pretty much the exact opposite.

I first heard about audiophile-quality class-D amps when I read Wes Phillips's enthusiastic review, in the August 2005 Stereophile, of Channel Islands Audio's class-D D-100 monoblock power amplifier. [Like the CIA D-100, the Sphinx uses class-D output modules from Hypex in the Netherlands.—Ed.] Wes raved on and on about the D-100's microdynamics and presence while driving three different loudspeakers. I was surprised, because weight, body, presence—and, especially, small-scale dynamics—are always at the top of my list of the things I most want an amp and speakers to do. But I still remember thinking, Class-D? What is the world of audio coming to? Well, judging by my experiences with the Sphinx, Rogue's owner and designer, Mark O'Brien, has taken this stigmatized, lower-class mode of operation to a new, more refined level.

A Rogue in the City of Light

The first record I played through the Rogue Sphinx was Aldo Ciccolini playing Erik Satie's Première Pensée et Sonneries de la Rose + Croix (LP, Angel S-36714). Ciccolini's firm notes approached me like staccato cat-paw steps. Dang! The left-hand register of the piano had more weight than I'd ever heard from the Totem Model One speakers. The piece's sad irony filled the room. I did not dance.

I just stood there. I forgot all about the Sphinx.

When the Sonneries finished and the nocturnes were kicking in, I thought, I could probably live with this amp for a long time. That thought came quickly because I believe that the primary purpose of high-fidelity equipment is not to distract the listener from the artistic intentions of the composer and musicians. The Sphinx accomplished this right out of the box. But . . . how?

I have never favored tubed over solid-state amplifiers. I always own and enjoy both. However, my experiences with a wide variety of amps have suggested that, as power ratings and damping factors increase, low-level detail, tonal color, subtlety, charm, and even soundstage dimensions seem to shrink. Surely there are grand exceptions to this rule, but to me, most amps of more than 30–60W output seem to summarize and reduce contrasts, especially through the midrange. When I installed the 100Wpc Rogue Sphinx, I had those expectations in mind.

At the start of my listening, I used the Sphinx with DeVore Fidelity's new Orangutan O/93 ($8400/pair) and Totem's Model One Signature ($2295/pair) speakers. Both models made it clear that this integrated amp could play lower, mid-, and upper bass—say, 40–120Hz—with unusual detail and authority. Bass attack, sustain, and decay with electric and acoustic instruments were clean, weighty, and articulated to the point of being almost distracting. Allusions to kick drum and the piano's left-hand register appear with multiple stars on every page of my listening notes.

Whenever my system is suddenly producing copious amounts of tight bass, I feel a need to gorge myself on it until I can't stand it anymore. So I reached for Daft Punk's Homework (CD, Virgin) and played it through twice. Still bingeing, I played Sunn O)))'s Black One (CD, Southern Lord SUNN50) all the way through. Then I tried the bass orgy of Aphex Twin's I Care Because You Do (CD, Sire 61790-2). King Sunny Ade and His African Beats' Juju Music (LP, Island MLPS 9712) immersed me knee-deep in waves of pulsing bass guitar. The Sphinx supported the party mood, the low power of the talking drums, and the texture of the dream-inducing keyboards on this album. Finally, ready to purge, I headed for the louche bars of Montparnasse.
The first time my mind really focused on the Sphinx's midrange was while listening to "La Vie d'Artiste," by the Parisian chanteur Leo Ferre, from Chansons de Leo Ferre, a 10" LP from 1953 (Le Chant du Monde LD-M-4022). The gentle piano and the loping, whispery rhythms of Ferre's singing were there for me to enjoy, his closely miked voice quivering and fluttering in air between the speakers. For a minute I listened critically instead of romantically, whereupon it became clear that the Sphinx was reducing the candlelit color and glowing vibrato of the sounds of both voice and piano—no more wet cobblestones, no fog surrounding those Paris gaslights. But, bloody French hell—this is a $1295 integrated, not some million-dollar drug substitute.




After Leo Ferre, I had no choice but to play some recordings by what Jean Cocteau described as a "terrifying little sleepwalker who sings her dreams to the air on the edge of a roof": Édith Piaf. Wondering what the Sphinx would do with the courage and big spirit of the Little Sparrow, I played what many call her last lament: "Non, je ne regrette rien (No, I Regret Nothing)," from More Piaf of Paris (LP, Capitol ST 10283). This is not a great recording, but it's a great song whose emotional effect depends almost entirely on forward-stepping momentum and drive. And, as I said at the beginning, the Sphinx "steps" with authority. The Sphinx driving the DeVore O/93s let me access the full texture and drama of Piaf's vocal art.

After stopping in the UK and booking passage on a steamship back to America, I installed KEF's LS50s ($1499.99/pair) in the system, and inserted John Fahey's Death Chants, Breakdowns and Military Waltzes (CD, Takoma TAKCD-8908-2) into the Puresound CD player. Instantly, I realized with certainty what earlier I'd only suspected: that the best of the Rogue Sphinx's many good features is its line stage. Everything I played was enjoyably detailed, transparent, and spacious. The Sphinx-LS50 combination took me by surprise by doing such things as room acoustic, image focus, guitar picking, bass plucking, and fiddle scratching better than I'd ever dreamed possible—even at double these prices. Now I was wondering: Could it be me? What if I'm incompetent, deaf, and gullible? What if the Rogue Sphinx is not nearly as good as I keep thinking it is?

Whenever a new component surprises or mystifies me, I reach for a recording I've played a thousand times through a hundred systems. Worried, I played a track by my favorite smart hipster women on synths: "Take Me as I Am," from Au Revoir Simone's Still Night, Still Light (CD, Our Secret OSRCO3). My anxiety ramped up. I had never experienced this volume or depth of bass. (I moved the LS50s three times to be certain that this enhanced bass wasn't a setup anomaly. It wasn't.) All types of new details appeared. With every track, I experienced big, vibrating air and microtextured reverb. I enjoyed it, but I was still worried.

Paris de la nuit
Seeking comfort and surety again in the City of Light, I looked up my childhood-fantasy femme and quickly remembered that I had not yet fully developed until I'd heard Brigitte Bardot sing Serge Gainsbourg's "Je Me Donne a Qui Me Plait," from her and God . . . created B.B. (CD, Hitland SML 015). Now I began wondering, What is it with these nouvelle chansons? I would think that playing them successfully would be all colorito and smoky atmosphere, but in practice, what these French singers needed was full-tilt momentum. No problem. What the Sphinx was best at was delivering forward musical movement. It also did weight and body. B.B.'s voice had a most tempting feminine presence.

I was lying on my couch, hanging with the avant-garde ca 1890, drinking absinthe at Le Chat Noir and listening to Erik Satie's ballet Mercure, with the Orchestra of Paris conducted by Pierre Dervaux (LP, EMI La Voix de Son Maåtre C 069-11677). It totally got hold of my mind. I was intoxicated. The Rogue's phono stage seemed lively, but a bit dense and opaque.

I exchanged the Ortofon 2M Red phono cartridge ($99) for the 2M Black ($719), which caused the Sphinx's phono stage to relax and open up. The ease and flow, and quirky mystery, of the Satie recording were now more accessible, and the Rogue felt more airy, liquid, and transparent. The soundstage expanded some.

Mercure features three sopranos and a mezzo-soprano, and this final system that I'd assembled—VPI Traveler turntable and tonearm, Ortofon 2M Black, Rogue Sphinx, KEF LS50s—reproduced their voices smoothly and elegantly. The sound was sweet. The contrasts between dark, solemn moments and bouncy, light-filled, free-dance passages were exciting to behold. High frequencies never drew attention to themselves.

How should I miss her?
For me, the best way to recognize what an audio component has brought to the party is to send it home and install another. While reinstating my beloved Creek 4330 ($495 in 2002), I noticed how solidly (and prudently) both were constructed. I also noted how neither company had invested in deluxe RCA jacks or speaker-binding posts.

When I played and God . . . created B.B. through the Creek, softer than the Sphinx was the first phrase that sprang to mind. Next came a little more distant. The beginnings and ends of notes became less distinct. Dynamic contrasts were reduced. But wait! Mlle. Bardot was suddenly more perfumed and sensuous, in her incomparable French way. I could see her standing on the beach at Cannes. Her smile made me smile.

Same with Daft Punk—the Creek amped up the color and atmosphere but reduced the scale and force of the bass. The 4330 made singers, flutes, and strings sound more plush but less corporeal. With the Creek, the dream factor was noticeably increased, the forward momentum and boogie factors clearly diminished. Hmm.


Integrated amplifiers are not like race cars. They are more like classic performance sedans: Engineered to be used and enjoyed over long stretches of time, the best such sedans showcase simplicity, traditional design, and durable high performance. Typically, they forgo some luxury options and put the savings into the engine, drivetrain, and suspension.

That's how I would describe the Rogue Audio Sphinx. I haven't spent time with the similarly priced integrateds from Arcam, NAD, Parasound, or Peachtree, but anyone studying the "Integrated Amplifiers" section of Stereophile's "Recommended Components" will notice that today's moderately priced integrateds offer an unprecedented number of alluring and competitive feature sets. I can imagine a young audiophile poring over this section, first comparing features and prices, and only at the end speculating about sound quality. Keeping that in mind, I suggest that the Rogue Sphinx's best features are the ones it lacks.

I went into this review with a clear prejudice against high-power class-D operation. I thought it would sound hard and generalized. I didn't think the Sphinx would effectively drive my 10-ohm DeVore Fidelity O/93s or my 15-ohm LS3/5As. I assumed that its phono stage would be nothing special. I was certain it would spoil my nuits à Paris.

I was wrong on all counts. The Sphinx played a wide range of high-quality loudspeakers with cunning authority. Its tubed line stage had a sound that was highly detailed, dynamic, and surprisingly transparent. Driven by a high-quality, high-output cartridge, the Rogue's passive RIAA phono stage was more than just okay or even respectable—it did high-speed boogie, air, and low-level subtlety.

In my full month of listening to the Rogue, I discovered the wisdom of its design. The Sphinx is all analog, which means that, five or even 20 years from now, everything the buyer paid for will still have value. If you upgrade your loudspeakers, that 100W amp should drive them without issue. If you get deep into vinyl, you can add a moving-coil step-up transformer—or even an outboard, super-quality phono stage into the Sphinx's line inputs.

Digital is evolving and improving so quickly that if you listen mostly to high-resolution digital, you might not want your integrated to include its own DAC. With the Rogue, you can add the modest DAC du jour and surf all the latest computer audio waves. Unlike the Sphinx's phono stage, whatever DAC these other integrateds come with will surely be outclassed and upstaged by something better—and sooner rather than later.

As I type this conclusion, I'm listening to the Ensemble Musica Nova playing the motets of Guillaume de Machaut (CD, Zig Zag-Territories ZZT 021002), with the Sphinx integrated driving the KEF LS50s via my most modest Oppo CD player ($170). I am experiencing genuine musical happiness. I don't need a million-dollar hi-fi. I just need a simple, no-nonsense integrated amp and some modest two-way speakers. Then, maybe, I can forget about audio, and be happy playing music for a long time.