Pre/Power Amplifiers

While the 9000P lifts the power amp from the 9000A integrated [HFN Aug ’23], it also benefits from an improved PSU and RF/EMI filtering. The 9000A also features an input trim for its gain to be adjusted over ±6dB from a default +23.1dB, so it’s no surprise the 9000P’s fixed gain is the same +23.1dB, requiring the same (balanced) 2V from a contemporary source to raise the rated 100W/8ohm output. In reality (again) the 9000P achieves more, delivering 2x113W/8ohm and 2x188W/4ohm with sufficient headroom to accommodate peaks of 145W, 270W, 285W and 155W into 8, 4, 2 and 1ohm loads, respectively, under dynamic conditions [see Graph 1, below]. The output is restricted into the lowest loads by a 12.5A current limit (re. <1% THD/10msec) while a mild Zobel network ensures stability into any load – this also sets the 0.03-0.08ohm output impedance (re. 20Hz-20kHz). Once again, the response is a wide –0.15dB/20kHz and –1.75dB/100kHz into 8ohm but droops slightly to –0.35dB/20kHz and –3.4dB/100kHz into lower 2ohm loads.

Distortion and noise remain very low, the latter improving on the 9000A’s 91.9dB A-wtd S/N ratio (re. 0dBW) to 92.4dB courtesy of the 9000P’s fettled PSU. Otherwise we see distortion, again, largely unaffected by power output (though it does increase with decreasing load) from 0.0004-0.0006%/1kHz over a full 1–100W/8ohm range. Versus frequency, distortion settles out at 0.00045–0.011% (re. 1–10W from 20Hz–20kHz), increasing slightly to 0.00055–0.026% at a full 75W/8ohm [see Graph 2, below]. Thanks to Audiolab’s optimised layout, with limited capacitive coupling between channels, the 9000P’s stereo separation is excellent at 71–93dB (20Hz–20kHz). PM