I regard Pioneer's A-27 as part of the elite group of ultimate vintage amplifiers.
That (personal) elite group is made of very few units : Yamaha B-1, Sony TA-E88B & TA-N7, Kenwood Model 700C & Model 700M and Luxman C-5000A & M-4000a.
I don't mention the Pioneer M-22 or M-25 since the A-0012 is largely based on the latter.
The A-0012 is in fact an expanded C-21 and M-25 put together :
Magni-Wide circuit, Class A/B output stage with RET transistors, DC everywhere, 200Khz bandwidth, a 32-step attenuator, vanishingly low distortion, two power transformers and selected componentry.
Plus very well balanced looks oscillating between massive and transparent.
All you need is love and all you need to listen to muisic is an A-27.