Copying this from the AudioShark page courtesy of Mike owner of Suncoast.
What we understand is that there are over 120 parts detail differences between the L-590aXII and L-595ASE;
* Different main power transformer, with special attention paid to noise entering the circuits. And with special vibration control of the transformer itself.
* New, special power supply capacitors. Also installed with special vibration control mounting.
* Anti-resonance chassis design elements implemented in the extreme.
* Peel coat PCB’s implemented where it can make a difference.
* Special copper clad critical signal path shielding.
* Special “Line-1 gold direct onto copper (KAPPA) alloy” RCA style input jacks. (For best sound quality)
* Special selected Nichicon and Nippon Chemi-Con capacitors used throughout.
* First introduction of Luxman’s proprietary “ODNF-u” (Only Distortion Negative Feedback – Ultimate) in an integrated amplifier application. (An advancement over ODNF 4.0)
* Special, very low -impedance speaker relays. (Higher damping factor= 370)