Bestseller from Luxman's hightime in the 1970s : its 50th anniversary !
No Duo-ßeta yet, but whole-stage DC-OCL and pure-complementary output with 2-stage differential amp. The first (differential) stage uses select transistors with high fT bandwidth and large COB ; the pre-driver stage is constant-current driven.
The eq section is basically equivalent to that of the C-1000 preamp ; the buffer amp is a 2-stage DC circuit and the tone controls are of the (typically LUX) NF type.
Also available in the same timeframe : L-80V (more powerful), L-85V (upper end), L-81 (somewhat similar to the L-80) and, Japan-only, L-90.
The 80V differs visually only by the balance knob (black plastic) ; the L-90 is a later incarnation from the YOSII period with a different controls placement and the absence of DIN connector.
Many nudies here ; a real L-80 here and a real L-80V here.