Foreshadowing the later Music Link Series : SC-22, PH-22, MA-22, similarily shaped MA-24, CD-23 or the close & distant cousin MA-7A.
Taking on the Model 15 of way back in... 1968 !
As anything named Ma, Sc, Sm, Pm or Tt, the Ma-5 bore the new Philips tag... somewhat : the Ma-5 had its roots in the (very last) Marantz USA design.
The Ma-5 had a long enough production run to have seen two versions : with the ESOTEC logo and without it.
Still, whatever, anyway - vivid little monoblock just the same.
Updated later in the 1980s as MA-6 and MA-7, mainly in Japan, then as MA-7A under the Music Link series, all three being full Marantz Japan products.
Also available, somewhat, as Sm-10 : two Ma-5s united by a 43cm front-plate - true dual-mono :)