Upper-mid integrated amp with one feature that set it apart in 1973 :
a phono MC stage... which however works with dedicated back transformer terminal (à la Luxman AD8000) so there is no MC stage inside per se but it's written on the faceplate :)
Said transformer was named DL-103T (for the DL-103 - no wonder) and cost very little (3400¥ in 1970) so it was probably made for earlier amps.
The rest is a slightly slimmed-down PMA-700 / PMA-700Z : one fairly big trafo, Motorola output transistors, DC output stage, two heatsinks/Darlington packs, two back MIC input pots with front mic mixing knob, null balance switch and a pre/main loop.
Updated as PMA-500Z in 1975 mainly without the MIC functions - but a sizeable price increase.
Then as PMA-500V in 1985 - but that's a really different item.
A real PMA-500 here and the updated version here.