I was playing with couple of additional details on the latest Arduino shield PCB (digital control of the PSU). The first one is to further reduce number of used MCU's GPIO pins. Four lines was used for CC and CV LED indicators (a pair per channel). I decide to move them to the TLC5925's outputs (IC1 on Sheet 1). That requires reducing number of power output LED indicators from two to one and reducing number of needed output lines from 6 to 3. One line was already available so in total 4 outputs are with such correction available.

Another more challenging detail is replacing Microchip's ENC28J60 with Wiznet W5500. Such change would improve the solution with the following features:

1. Full and half duplex mode, auto negotiation
2. 10 and 100Mps connection speed
3. 32KB buffer memory
4. Reduced memory and MCU processing power usage

The price difference between them is almost non-existent (see ENC28J60 and W5500).

I got yesterday W5500 module from eBay and connect it to the Arduino Due:

It works "out of the box" and both power (+5V) and signals (+3.3V levels) are directly supplied from the Due. As chip select Digital pin 10 is used (SS) and thanks to Soohwan Kim (embeddist) library that is available on the GitHub I successfully tested few scenarios such as DHCP connection, Web server and NTP client.