Alongwith the C-5000A, the L58A is probably part of of the classiest Luxmans ever made.
It also held the staple (and then new) Duo-ßeta circuit plus another novelty : high fT Mos-Fet power transistors !
Also a contemporary fad : sharkfin heatsinks.
Also Fet input stages, DC structure all over, 300mA (!) of bias for Class A 99% of the listening time, SEPP Fet bootstrap cascode equalizer circuit for low distortion and higher slew-rate, film caps, DC Servo on the 2nd Beta loop, low open-loop gain, buffer amplifier before the Lux NF tone controls, power caps bypassed by film caps (again), low-impedance and fully-regulated preamplifier section and constant-voltage regulated pre-driver and output stages.
Convenience-wise : stereo/reverse/mono switch, pre/main separation i/o, two-position low-boost, two-position high and subsonic filters, two-way tape dubbing & monitoring, tone bypass and Luxman's traditional feather-touch muting pad (the lit round surface above the source selector) which works as in the L-100.
The chassis and wooden enclosure are designed to "fit" the circuit boards and limit the amount of metal that could induce eddy current distortion.
The less powerful but visually identical L-55A (1979) is built a bit less lavishly (inside) but retains the Duo-Beta circuit ; it shares its service manual with the L58A.
The slightly later (1980), bigger and even more beautiful L-68A is an upgraded L58A with even better componentry, even less distortion, a bit more power, a redesigned MC board and, mostly, the Plus-X circuit and Line Phase Sensor added.
Luxman pushed hard its new baby, making it the center of its stand at the 1979 Japan Audio fair.
Despite being priced at the low limit of high-end audio (by japanese standards), the L58A is, to me, part of Luxman's all-time transistor best : design, sound and reliability make for a timeless classic. And the L-68A is even better.
Also available in the USA as L-580 with added meters à la M-120A ; this was a Lux Corporation of America request so it isn't mentioned anywhere else - but do not mistake this for the 1994 L-580 !
You may see a real L-58A here, a real L-55A at the indispensable amp8.com and a real L-68A here.