As I remember, when Proton first appeared NAD was already established, though not long. The similarities were immediately noted. It was said they were made at the same factory, Funai in Taiwan, with much interbreeding. Even that Proton was a "higher-end" subsidiary of NAD — "higher-end" basically meant better parts and much stricter QC, which NAD at the time was infamous for lacking. I never heard the name Fulet before.
This is just FYI what the UK magazines were saying at the time, I don't verify it.