Pre/Power Amplifiers

Some brands are more conservative than others when it comes to specifying power output (and speaker sensitivity!) but Audiolab is flying quite close to the wire with its 50W/75W 8/4ohm rating for the 6000A. With a high 246V AC mains feed it manages 2x55W/2x85W, respectively, but we've seen other 50-watters achieve 70-80W/8ohm in practice. Nevertheless, the PSU is sufficiently 'relaxed' to support a far higher 71W and 133W into 8 and 4ohm loads under dynamic conditions, albeit with some restriction to 99W/55W into lower 2/1ohm loads [see Graph 1, below]. Otherwise, the A-wtd S/N ratio is very generous at 92dB (re. 0dBW), the output impedance usefully low at 0.01ohm and the response very extended, reaching 20Hz-20kHz (±0.1dB) and out to –1.6dB/100kHz. Distortion is also very low at ~0.0004% through the bass and then increases gently to 0.001-0.006% in the midband to ~0.03%/20kHz and 0.06%/40kHz.

The onboard DAC stage is certainly no afterthought – tested via the preamp output (a maximum of 2.8V being available here) – it delivers a performance that's commensurate with most ESS9018-based outboard DACs at £500. The A-wtd S/N is a wide 109dB and low-level resolution is good to ±0.2dB over a 100dB dynamic range. Jitter is exceptionally low at <10psec across all sample rates and distortion is not only as low as 0.0005-0.0014% at –10dBFs (20Hz-20kHz) but is also very consistent with frequency below –20dBFs [black vs. blue traces, Graph 2]. With the default linear phase digital filter option, stopband rejection is a full 83dB and the response reaches out to –0.2dB/20kHz (CD/48kHz media) with –1.3dB/45kHz and –3.7dB/90kHz realised with 96kHz and 192kHz files, respectively. PM