I had to add a reply The PDS-703 was the first cdp I ever tinkered with, infact it was the first thing that got me into diy!
Good memories

No, thats not my cdp for sale BTW, I got rid of mine years ago
I remember one mod I did was to do with the filtering before the op-amp stage, then the standard op-amp could not cope with it so I upgraded that next.
I then did some tinkering with the psu, I then fitted a Trichord clock.
It was a good learning experience, a mate I gave it to later was well chuffed with it, he actually liked it better than his Arcam Alpha9