The integrated version of the Sm-6 : same specs, same weight, same Heat-Pipe cooling system.
Available in Japan with a wood-enclosure and updated as Pm-6a, with a Quarter-A circuit, the original remaining far more successful despite a somewhat "dated" design - by early 1980s standards.
Only the early units have the Marantz ESOTEC tag on the upper right of the front, gold in the USA, black in Europe ; later ones only have Pm-6 written.
Marantz had lost the name's © which had been previously registered by another company... but Marantz sold at least half a million Pm-6s so it worked nevertheless.