Pics showing all the mods/upgrades done so far - I had to replace the VAM1202 transport yesterday, so I used the opportunity to a complete a few pending upgrades. The only mods not visible in this pic are a few SMD bypass caps installed on the underside near the DAC, and a jumper wire. Most of the mods in the PSU and Digital section are simple replacements of electrolytics and bypass caps with better quality ones. Nothing very boutique-oriented, just a bunch of Sanyo Oscon SCs for the small digital bypasses, and a pair of Panasonic Pureism PXL for the main analog rails after the regulators. All the regulators have been left unchanged.
Most of the key mods are centred around the DAC, PWM filter and Line Opamp.
The Analog supply to the DAC is separated from the Digital +5V rail and derived from the Opamp +12V rail instead, and regulated further with two independent shunt regulators for the two channels. The outputs of the shunt regulators are bypassed with NCC PSA polymer caps close to the SM5872 DAC analog supplies, and there's also 4x X7R SMD ceramics directly on the analog supply pins of the DAC. The XTAL circuit is cleaned up with improved routing and bypasses, but its supply is still derived from digital +5V (I may put in an external Tent clock or Kwak clock later, so I didn't want to waste too much time on the DAC internal XTAL supply).
The PWM filter has Wima FKP2 stacked film/foil caps at almost all locations - there is one additional silver mica in each channel, used as the cross-coupling element suggested by Mauro Penasa. Almost all the resistors have been left unchanged (they're 0.125W and small, and all my better resistors like Dale, PRP, Welwyn, Holco, Philips etc., are larger sized and will have to be mounted vertically, which will increase the lead inductance, so that's been deferred for now - I may consider using thin-film SMD resistors on the underside in a future upgrade).
The main change is the opamp - I removed the original JRCs, soldered 2x DIP8 sockets, and used the latest version of my LF03 fully-discrete dual opamps in the socket. These are bypassed by 4x 220uF/25v Cerafines from each rail to ground. In addition, there's a rail-to-rail SMD PPS bypass on each channel of each LF03 opamp.
The final mod is to completely disable the HDAMs - they're still on board, but the signal is sent directly from the opamp to the RCA out. The 4x Elna Silimic DC-blocking/coupling caps are also removed.
That's about all that's been done, and the results are sufficiently good for me to consider stopping here - only the low-jitter external clock mod has been left for future consideration. Note that there's no clutter on the board in the form of additional large boards, dangling wires, oversize capacitors, large film caps, etc., which is the norm in many of the mods posted on the ~2000-page diyAudio thread.
The sound? Very transparent, open and micro-detailed. It's just a trifle bright in the upper mids. It may settle down after the Cerafines run in - if it still remains bright, I'll upgrade the Cerafines to Black Gate PKs after a few months (not a single Black Gate has been used in this CDP upgrade).
The same set of mods can be performed on any Marantz with an NPC SM5872 DAC - this includes the CD43/53/63/67/1020 and all derivatives.
