Apologies for answering a question that wasn't aimed at me, but I got tv's meaning right away. As this, and the associated 'Transistor Equivalent' thread, are about making HiFi amps, various commercial amplifiers have been discussed along the way because they have characteristics of note: Leach, Self Simple, Mission Cyrus 1 & 2 and so on. tv is, quite interestingly pointing out, that the NAD 3020 is a milestone audio amplifier of great merit as highlighted by this extract from the Wikipedia page on the NAD 3020:
The
NAD 3020 is an iconic stereo
integrated amplifier by
NAD Electronics, considered to be one of the most important components in the history of
high fidelity audio.
[1] Launched circa 1978, this highly affordable product delivered a good quality sound, which acquired a reputation as an
audiophile amplifier of exceptional value. By 1998, the NAD 3020 had become the most well known and best-selling audio amplifier in history.
[2]
https://en.wikipedia.org/wiki/NAD_3020
spec
PS: For those still swayed by audio amplifier technical specifications: total harmonic distortion (THD, inter modulation distortion (IMD), noise, damping factor etc, etc, there is a very telling sentence, also from the Wikipedia article on the NAD 3020:
NAD eschewed the laboratory test equipment thinking, which was prevalent at the time, and instead aimed to make their amplifiers capable of properly driving "real loudspeakers" under realistic conditions. This paradigm shift gave rise to an amplifier that cost less and sounded better.
[10][11]