Yamaha M-2

All things must pass - gone were the V-FET, long live the High-fT !
High-fTs are made of multiple miniature transistors connected in parallel, offering lower switching distortion and a high frequency cutoff (High fT) up to 80MHz, thus offering better linearity.

Just like Sony, Yamaha dropped the expensive Vertical FETs for cheaper ones... which Sony used as well in many of its own units, from the 1977 TA-N86B onward. Just as for the VFETs, both Sony and Yamaha touted that the High-fT were exclusive designs of their respective R&D labs :-)

Released in Japan as a B-5, without the meters, but an impedance output level, as found in earlier and contemporary amps like the CA-S1. A very healthy power amplifier anyway, with a keyword : p o w e r.
The chassis, heatsinks, toroidal transformer and internal structure (but not necessarily circuits) were reused in the later PC2002 and PC2002M professional amplifiers (here), both of which came from the P-2200, a july 1976 bigga PA amp.