All Sony units launched in 1992 and 1993 to celebrate the 10th anniversary of the CD format can be summed up with one word : maturity.
For half the price, you'd get 90% of a CDP-X707ES.
What you did not get was ultimate details : Twin-Core transformer, XLR outputs, the coaxial digital out or a super-beefy power-supply.
What you did get on top of a truly unbeatable bargain was a complex system of CD filing called "Custom File", all sorts of programming modes... and a lot more buttons on the front.
However, the rest is nearly the same as a CDP-X707ES : "G" base drive, "G" tray, GIC analog LPF, sapphire bearing and BSL motor, copper-plated chassis 'n all - and the bargain worked very well for there are thousands of X505ES and 555ESJ still playing around the world.
The digital filter was upgraded from the previous CDP-X559ES which used a CXD-2560 : in came the CXD-2567 which was of the SCORE type. SCORE, btw, stands for "Subliminal Correlation" ; the same d/a IC however was retained (CXD-2562) just as the KSS-272A laser block.
Available as CDP-X505ES worldwide until late 1994 and CDP-555ESJ in Japan until late 1993 : the X505ES in black with matte square sideburns or gold with shiny rounded sideburns, the 555ESJ with rounded sideburns whether the player was black or champagne.
12,5 kilos of long-lasting, excellent sounding and affordable high-end.
Nudies of the CDP-555ESJ here.