Integrated Amplifiers

There’s no DAC stage built into the WSH-805, but this is still an amplifier of two halves with a choice of an 80W-rated Class AB output or an 8W-rated Class A output. And the latter is the ‘real deal’ – switching between Class AB and Class A modes sees the idle draw increase from 42W to 129W while the power output clips at 10W/8ohm and 18W/4ohm with 10W, 19W, 34W and 50W available into 8, 4, 2 and 1ohm loads, respectively, under dynamic conditions [dashed traces, Graph 1]. Distortion is lower under steady-state than dynamic conditions, but not meaningfully lower in Class A over AB mode at 0.00075-0.002% vs. 0.00045-0.004% [dashed grey and solid black traces, respectively, Graph 2, both re. 20Hz-20kHz, 1W/8ohm]. Neither is the sensibly moderate +31dB overall gain, the above average 89dB A-wtd S/N ratio, the 0.065-0.088ohm output impedance or –0.35dB to –0.24dB response (re. 20Hz-20kHz) changed by switching between Class AB or Class A operation.

The WSH-805’s Class AB power output is significantly higher than in Class A mode, of course, the former meeting Unitra’s 2x80W/8ohm and 2x125W/4ohm rating at 2x86W and 2x148W, respectively, while upping the ante to 109W and 185W under dynamic conditions [see Graph 1], below. Current-limiting, and electronic protection, restricts the output to 135W and 89W into 2 and 1ohm loads, suggesting the WSH-805 won’t get into trouble but, equally, neither is it best suited to tougher, low-impedance loudspeaker loads. Also, if you are not going to use the tone controls, the ‘Linear’ switch is recommended as the default ‘0’ bass/treble positions are not flat, the response showing a broad +0.4dB boost through the presence band. PM