MEASUREMENTS

I measured the Devialet Expert 140 Pro using my Audio Precision SYS2722 system (see the January 2008 “As We See It”¹). The amplifier as received was set to “High Pass 10Hz, Max. Level 2.0V.” I usually precondition amplifiers by running them at one-third power into 8 ohms for an hour, which is thermally the worst case for a class-AB output stage. As the Devialet has a (partly) digital output stage, the preconditioning wasn’t necessary. Nevertheless, the amplifier ran warm, with the top panel measuring 119.9°F (48.9°C) an hour or so into the testing. The menu’s internal temperature function indicated the message “Temp. A Amp 61°C; Temp. D Amp 57°C; Temp. Supply 65°C.” The Expert 140 Pro should be positioned where it is well-ventilated.

As I always do with class-D amplifiers, I inserted an