First of the post-Alpine AZDEN period, the L-500 is the last of the L-550 series.
And like the previous L-570 or the later L-580, the 500 outputs music in pure Class A only.
Differences lie in the looks, internal circuit, transformer and, mostly, the attenuator : the latter, named "ultimate attenuator", is a big box holding two glass-epoxy PCBs etched with 32 non-magnetic P-shaped gold resistors.
In other words, a device like that of the Sony TA-E88B ('76) or the Sansui C-2301 ('84), also encased in a non-magnetic diecast aluminium box.
The power-supply is more common that that of the L-580 (no Heat-Pipe) and there is no phono stage either.
The circuit is all-DC pure complementary with Duo-ß and Star earthing circuits.
Also in are, naturally, a Line-Phase sensor, NF tilt tone control (like an L-100 or L-309), non-resonant FRP base, gold-plated terminals, styrol "custom" caps and all one can expect from a "limited edition" Lux amplifier.
A real L-500 here.