Your CD uses one of the best chips ever produced, the TDA1541-A and is still sought after and used in some very expensive units, for example the SW1X lll @ $5999 who claim the chip to be the most analogue R2R ever.
So mod away and enjoy a huge sonic return. I read and corresponded directly with Lukasz Fikus of Lampizator fame. About 15 years ago I modded my flimsy little Marantz CD40, they can be found unloved and unwanted on ebay for about 30 bucks and are great for mods because of the space inside. Not much there so accommodating a small transformer and a pair of valves is easy.
Basically you come straight off the DAC pins that are signal out and connect them to the grids of an ECC88 or similar. Lukasz' favourite appears to be the 6N6P. And by cutting 2 tracks of the PCB can be rendered NOS (recommended) By doing this you are eliminating lots of noisy circuitry and avoiding the common opamps used for this purpose.
If this all sounds a little daunting it's not and is why I mentioned the CD40. My suggestion is to find one of these cheaply to experiment with. Many players with the TDA chip can be used, like Philips players which can be found in the skip. Marantz/Philips use the same mother board on dozens of different models. Example the Marantz CD40 internals are exactly the same in the CD50 and CD60, just the exterior and chassis differ slightly withe the model 60 having a gold coloured face-plate.
The result of this mod will really delight you and provide you with the confidence to mod the CD75 which you can go all out on if you so choose. My CD40 had bitumen adhesive damping, new quality RCA connectors and solid core wiring. I was so impressed and actually giddy with joy that I built a new power supply for it using an EZ80 rectifier with choke input and Panasonic TSHA 105 degree caps in a separate enclosure connected by an umbilical. I threw out the old power cable, mounted a gland on the back for the new cable and soldered a better one in place. Stunning!
The links I provide take you to the Lampizator site which details with many photos how to go about it. Additional caps around the chip are added by simply soldering them across the underside of the PCB, easy peasy.
Even folks not interested in modding can find tons of useful info here.
http://lampizator.eu/LAMPIZATOR/TDA1...r/TDA1541.html
http://lampizator.eu/LAMPIZATOR/Lampizator.html (find hyperlink to: Lampizator DIY step by step for beginners)
His site needs patience but hang in there, it's worth it.