measured the C 3050 LE using my Audio Precision SYS2722 system. As the NAD is a class-D design, I didn’t precondition the amplifier by driving a 1kHz tone at one-third power into 8 ohms. Nevertheless, before doing any testing, I ran it for an hour at a moderate power level to ensure that it was fully warmed up. At the end of that time, the temperature of the black grille on the top panel was 92.1°F/33.4°C. Because class-D amplifiers emit relatively high levels of ultrasonic noise that would drive my analyzer’s input into slew-rate limiting, all the measurements other than frequency response were taken with Audio Precision’s auxiliary AUX-0025 passive low-pass filter, which eliminates noise above 250kHz. Without the filter, 294mV of ultrasonic noise with a center frequency of 413kHz was present at the loudspeaker terminals. This noise was also present, at a much lower level, at the headphone
