@rogerstaton I am looking at Pro-Ject and Heed CD transports with I2S to connect to my new Holo Audio Spring 3 v2 DAC.
The problem as you noted is the lack of an industry standard protocol. For example my understanding is that Pro-Ject is proprietary and only seems compatible with its sibling DACs.
If true then regrettable. Such an excellent sounding CD transport should have as much universal utility with other brands as is possible. I use my Pro-Ject RS2T via Spdif to my DAC and it’s splendid.
Charles