I performed the measurements of the Rotel RA-6000 with my Audio Precision SYS2722 system.1 I preconditioned the amplifier by operating it at1/8 power into 8 ohms for 30 minutes. At the end of that time, the temperature of the top-panel grilles over the heatsinks was almost too hot to touch, at 130.4°F/54.2°C. The RA-6000 needs to be well-ventilated.
Looking first at the line-level analog inputs, the Rotel RA-6000’s maximum voltage gain from the loudspeaker output at 1kHz into 8 ohms was 22.14dB for the balanced input and 27.8dB for the unbalanced inputs. For the latter, the maximum gain was 1.28dB from the Pre output and 27.84dB from the headphone output. The amplifier preserved absolute polarity, ie, was noninverting, from all its outputs. The balanced input impedance was close to the specified 100k ohms, at 94k ohms at 20Hz and 1kHz, 90k ohms at 20kHz. The unbalanced input impedance is specified as 5.6k ohms; I measured 5.65k ohms at 20Hz and 1kHz, 5.5k ohms at 20kHz. This is on the low side; tubed components with a high
