This morning, I received an email from John, my DIY friend in Europe, saying how happy he was. He had just finished building a new power amplifier using two UcD250LP class-D amplifier modules. He described the results as “quiet, clear, clean, effortless class-D power,” adding, “What more could I ask for?”
I am slow on the uptake, so I thought my friend’s question was sincere, not rhetorical. Moments later it hit me: This is a question I should try to answer in this review of the Rogue Audio Pharaoh II amplifier. Beyond the virtues John described, what more, indeed, could we ask for?
In closing, John mentioned, “Later, I might build a tube input buffer for it, but for now I am happy.”
My Euro friend’s letter reminded me that in last month’s Audio-GD DAC review, I speculated that most digital designers are probably trying to make their DACs sound like analog. (I mean, duh! What’s the alternative?) Then, this month, as I installed the Pharaoh II tube–class-D hybrid amplifier, I wondered: How many class-D amplifier designers are trying to make their small, light, cool-running amps sound like hot, heavy, high-power class-A amps? Or like glowing tubes?
The sound was elegant and pristine, with exquisite fine detailing set against silent backgrounds.
That vein of thinking led to another question: What is it I relish in class-A amplifiers that I don’t get from class-D amplifiers? And what about triode tubes? Why is their effect so mesmerizing?
My answer to the class-A question is, first and foremost, that I always want amplifiers driving my speakers to deliver a natural, lifelike tone; anyone should be able to hear it. Instruments, voices, and recording studio effects should sound conspicuously like themselves. Natural tone is the trait I seek above all, in all audio gear, but it is not the first trait that comes to mind when I think of class-D, which I primarily associate with slam, deep bass, and paranormal clarity.
Along with natural tone, class-A amps specialize in recovering the microdetail and nanotextures that inhabit every
