Rogue Audio Sphinx Tube Hybrid Integrated Amplifier

Class D With A Difference

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

Use and Listening

I’ll be honest. I don’t have a clue why the Sphinx sounds as good as it does. The obvious non-answer is good design and carefully chosen if not super-premium parts. Mark uses a pair of JJ Electronic 12AU7 tubes in the preamp section and Hypex UCD180 Class D modules for the output stage. Important to making this all work well is the power supply, according to Mark, who uses a fairly hefty toroidal transformer from Avel Lindberg. The headphone circuit has its own discrete amplifier section and is the same one used in Rogue’s more expensive preamps.

While there are none of the sometimes very steep tradeoffs I’ve learned to accept if I want cheap and good sound, the need to make some accommodations with respect to the user interface is still present. The materials and fit-and-finish of the Sphinx’s faceplate and controls are competitive for this price sector, but anyone who has had even the briefest experience with, say, a McIntosh or Accuphase control amplifier will be reminded of the massive engineering effort that can be devoted to issues that have nothing to do with sound.

So soft-touch controls and microprocessors are absent. Instead, the stand-by power switch is a hefty spring-loaded affair, while the source-selector feels both stiff and a bit spongy due to the long torque tube spanning the deep 17" chassis. Sorry, there is no tape loop, but the Sphinx does accept up to three line sources and has a moving-magnet phono input. A balance control is welcome, as is the optional motorized volume control ($100), which quite commendably worked without overshoot. With this option, the all-metal dedicated remote volume control is large, heavy, and all business. Drop it on your big toe and you’ll know it!

The EIC power socket, the main power switch, widely separated three-way binding posts, and surface-mount RCA connectors on the back panel make good use of the plentiful acreage found there. Nearby is a pair of fixed and variable line-level outputs suitable for processors, subwoofers, external headphone amplifiers, or power amplifiers. Speaking of headphones, I found the built-in headphone circuit to be sweet sounding and very refined, yet I could have used a little more gain to better suit my power-hungry Sennheiser HD 600s.

Some operational notes before I get into the sound. Mark designed the Sphinx to be energized in stand-by mode, but that doesn’t apply to the two input tubes, which only see current when you throw the front-panel “power” switch, and are then slowly ramped up to full power—a process that takes about 20 seconds. It might not be the craziest thing to buy the Sphinx for its phonostage alone, for it really is that good. Dynamic, spacious, quiet, possessing very good resolving power, it is a simplified version of the circuit used in Rogue’s solid-state Triton phono preamp, and it made for a splendid fit with either of my moving- magnet cartridges.

Be forewarned, though, as you may find some of your old vinyl favorites no longer listenable. I had to chuck up the dough for a fresh pressing of Dark Side of the Moon [Harvest SHVL 804] thanks to the Sphinx’s ability to demonstrate just how noisy my three-decade-old edition had become. Annoying, but I can’t shoot the messenger. So how does the Rogue sound on the new record? Well, DSM is, of course, a creation of studio wizardry but its fame as the hi-fi demo record for the last 40 years is justified. Floor shaking heartbeats? Jet airplanes leaving the tarmac? A cacophony of alarm clock bells? Gorgeous female vocals? They were all there, fresh as the day I first heard this masterpiece of 1970s pop-art. The Sphinx also found a way to make my mono soundtrack of Porgy and Bess [Columbia] sound fresh, vibrant, and vital, even after 54 years. Adele Addison’s performance of “I Loves You, Porgy” (her voice was used to dub that of the film’s star Dorothy Dandridge) is brief but oh so devastatingly lovely.

If you have no use for a phonostage, the Sphinx would still be a bargain for the price. (Mark might even change out the phono circuitry for an extra line-level input if you ask him nicely.)