Pioneer Exclusive M4
(1974 - 1979)

Huge Class A powerhouse and true bestseller for Pioneer: the M4 could be seen in many many many high-end rigs of the times. So successful that it remained available for almost 5 years, until the updated M4a was launched (1979) and ultimately the Exclusive M5 monoblock (1982) .
The Exclusive M4 is a Class A version of the already popular Exclusive M3: same basic design, same power transistors, same looks, same weight... except: it puts out 2x 50W in pure Class A from 20Hz to 20kHz - room-heater ahead! Absent from the M4 are the three speaker pair terminals and input level pots ; the pre-driver stage is also simplified.

At any rate, this is what educated high-end should look and sound like - the audiophiles of the time didn't miss it.