Alas very rare but part of the first period LUX design masterpieces. And the WL-202 companion tuner is even better.
The phono section is an NF (negative feedback) type 3-stage direct coupling system ; special input transistors allow high input level.
The 2nd stage is a two-channel differential amplification with an emitter-follower circling the attenuator.
Filters and tone controls also are of the NF kind and PRE output impedance remains low at 100 Ohm.
The power section has an emitter follower circuit again, setup as 1st stage to make the input sensitivity variable ; the output section is a DC SEPP full complementary system with 2-stage differential driving circuit and dual power supply.
The features and functions are multi-galore : selectable center-frequncy tone controls, front tape and MIC inputs with respective monitor switch and input level pot & MIC mixing, stereo / reverse / mono L / mono R / mono L+R selector, two low cut and two high cut filters, volume-varying loudness, separable pre/main loop, input level pots for the MAIN in and aux 2 inputs, 3-position selectable phono 2 impedance, five inputs and two tape loops (plus the front) !
And the meters can be (back) switched between PRE levels or Main 0dB and Main -14dB display, too.
I think no other manufacturer ever tried as many possible combinations of layout for the secondary functions as Luxman did - Sony included.
Following the iterations of layouts from the SQ38D to the 202, L-11, L-58A, L-550, C-300, C-05, L-570 or C-06 makes for a nice lesson of how to do things properly. If ever differently !
The wide center-row of switches would resurface later in the 1970s with the L-5 series, in many export-only receivers throughout 1979/1981, then in the L-400 series in 1981.
The SQ202 saw a Bic/Lux receiver version named 71/4R - that's right : a 202 with an AM/FM section added ! Ultra-rare to say the least and another proof of Luxman's really crazy production schemes.
Fiddly fingers, twinkly eyes, happy ears... the SQ202 is b e a u t i f u l.