Part of the myriad of Luxman vacuum tube integrated amplifiers - with a twist : absolutely non-tubey looks, matte sub-panel and coloured backlit pads !
Much closer to contemporary LUXKIT units than a regular SQ-38FD - which is normal since the LX33 had a Luxkit semi-equivalent in mid-size format (but not circuit - A505) and a 99% equivalent (Luxkit A1033) which had a standard 2-gang ALPS volume pot instead of the better "blue-box" ALPS inside the LX33.
Luxman advertised a little for the A505, not at all for the A1033 but at length for the LX33, at length.
Maybe why it sold so well - or not !
Do note that LX33 is written à la Luxkit (no dash between LX and 33) which may point toward Luxkit roots, like the CL-34 (or CL34).
The LX33 was apparently exported and OEM'ed by Luxman in the USA under the FujiTech tag for the Monarchy Engineering brand - another crazy Luxman distribution scheme !
The preamp (phono) stage is a 2-stage P.C. NF circuit with a 12AX7 ; negative feedback is looped to the cathode at the 1st stage from the following plate for low distortion and high-bandwidth stability.
The driver section is a Mullar driving circuit (cathode-coupling phase-inversion circuit) and all amplifying stages are done with triodes : one 6AQ8 for the first stage and two 12AU7 for the driver.
The output section is made by a quartet of 6CA7 pentodes in push-pull with Ultra-Linear coupling ; two OY15-5KF transformers feed all.
NF tone controls (basic bass/treble, though), and "modern" features make the LX33 usable in a "modern" way : tape monitoring/dubbing, separable pre/main sections, balance and stereo/mono switch.
"To cater for the specific requirement of sophisticated audiophiles this model is designed under full command of perfect knowledge about vacuum state technology of existing tubes.”" - is what is written atop the model number.
This 1979 renewed call for modestly priced tube amplifiers sounds quite prescient, thirty years after the LX33 : tubes are still around with many 6CA7s and 12AX7s making music for the pleasure of our (educated) ears.
A real-life LX33 here, another one here.
The Luxkit A1033 version is visible here and the A505 sibling here.