I performed measurements on the Roksan Attessa with my Audio Precision SYS2722 system.1 I preconditioned the amplifier by operating it at 1/8 power into 8 ohms for 30 minutes. At the end of that time, the top panel’s temperature was 108.4°F/42.4°C and that of the grille over the heatsinks almost too hot to touch, at 134.4°F/55.9°C. The Attessa needs sufficient ventilation.
Looking first at the line-level analog “Variable Input” and with the sensitivity set to “Low” with the MaestroUnite app, the Roksan Attessa’s maximum voltage gain at 1kHz was 34.9dB from the loudspeaker output into 8 ohms, 5.85dB from the Pre output, and 11.85dB from the headphone output with the sensitivity set to “Mid.” The amplifier preserved absolute polarity, ie, it was noninverting from its loudspeaker, headphone, and Pre outputs. The input impedance was 25k ohms at 20Hz and 1kHz and 23.6k ohms at 20kHz.
The headphone output’s source impedance was a usefully low 6 was just ±0.1dB (fig.1, gray trace). Into resistive loads (fig.1, blue, red, cyan, magenta, and green traces), the Attessa’s frequency response rolled off above the audioband. The fastest rolloff was into 2 ohms (green trace), the output being down by 3dB at 39kHz. There is the beginning of a boost at frequencies below 20Hz in this graph; the measurements in our sister magazine indicated that this boost reached +9.2dB at 3Hz.
