Speakers

Hands On: Theta Digital Earns High Marks for Prometheus Amp

CE Pro senior editor Robert Archer reviewed Theta’s Prometheus amp, which includes balanced XLR and unbalanced RCA inputs as well as balanced Cardastype outputs that allow for bi-wiring.


Hands On: Theta Digital Earns High Marks for Prometheus Amp
Theta Digita Prometheus Class D Monoblock Amplifier

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Robert Archer · December 15, 2014

Theta Digital has earned a reputation as a premier audio brand through the success of its DACs (digital-to-analog converters) and transports during the early years of the CD format, and its high-powered amplifiers. Keeping up with market trends that include the renaissance of vinyl and the emergence of digital streams and downloads, the company recently released its Prometheus Class D monoblock amplifier.

Theta’s chief engineer Dave Reich collaborated with Bruno Putzeys of Hypex to develop the amp’s Class D architecture. According to the California company, the amp (MSRP $6,000 each) is engineered to be “load agnostic’ and its frequency response is “load invariant.” Theta claims the amp produces less than 0.01 percent harmonic distortion at 500 watts into 4 ohms, and its output impedance and damping factor provide absolute control over speaker drivers.

Theta incorporates XLR and RCA inputs, 12-volt triggers and Cardas-type binding posts that will accept bi-wire configurations. The amp is rated to deliver 250 watts into 8 ohms, 500 watts into 4 ohms and 850 watts into 2 ohms, which means it can drive just about any loudspeaker without causing damage to it or the speaker. The amp features the company’s established industrial design, and comes in black or silver.

Setup couldn’t be any easier. Despite their size the amps are relatively light and easy to handle thanks to the Class D electronics. I placed them near my speakers and ran a set of Transparent speaker cables from the amps to my Monitor Audio PL 100s. My next step was to run XLR cables from the amp’s inputs to my Bryston preamp. Rearpanel connections are very accessible. I finished the setup by plugging the amps into a Richard Gray’s 1200S power conditioner.

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Using sources that included an Apple TV connected to a Meridian Direct DAC and Avid’s Acutus SP turntable connected to a Cary Audio PH-302 MKII phono preamp, I was able to run the amps through about 75 hours of break-in before I sat down for some formal listening.

Playing everything from Lisa Loeb, Led Zeppelin and Diana Krall, to AWOL Nation, David Bowie and the Cars, I was elated by the smoothness and effortless nature of the amps’ power capabilities. The soundstage is enormous and its noise floor is extremely low.

Through the Avid/Cary/Theta combination, I found the bottom end on analog playback to be punchy and well controlled, the midrange detailed with high amounts of texture reproducing instruments such as guitars and drums, and the top end well balanced.

Just listening to the Cars’ first LP for example, I thought that record sounded as good as I’ve ever heard it. The rawness of the Elliot Easton’s guitars, the natural tonality of Ric Ocasek’s voice, the snappiness of the bottom end, and the pinpoint accuracy of the image made the record sound immense.

As for digital content, I listened to a variety of Apple Lossless (ALAC), AIFF and AAC files upsampled through the Meridian DAC. On tracks such as Pink’s “Who Knew” in ALAC format I thought the amps helped produce an amazing amount of micro-dynamics with the bass exuding a nice attack and lots of fullness, plus a gigantic soundstage.

My only knock would be that I did hear some initial upper midrange edginess, but with break-in that disappears.

Anyone who has preconceived notions that digital amps aren’t as good as traditional linear-power supply amps needs to hear the Prometheus. The amp can be thought of as a two-channel product, but I see no issue with its ability to integrate into a home theater, as long as the client doesn’t mind the footprint of multiple amps. For dealers the Prometheus represents a fantastic way to provide a state-of-the-art design that delivers state-of-the-art sound quality.

CE Pro Verdict

PROS: Big and warm sounding like a traditional Class A/B design; effortless power on demand; easy to set up and compatible with just about any audio system
CONS: Somewhat large; price will preclude some consumers



  About the Author

Bob is an audio enthusiast who has written about consumer electronics for various publications within Massachusetts before joining the staff of CE Pro in 2000. Bob is THX Level I certified, and he's also taken classes from the Imaging Science Foundation (ISF) and Home Acoustics Alliance (HAA). In addition, he's studied guitar and music theory at Sarrin Music Studios in Wakefield, Mass., and he also studies Kyokushin karate at 5 Dragons in Haverhill, Mass. Have a suggestion or a topic you want to read more about? Email Robert at [email protected]

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