what I can say is that using the Philips CD player (has a CD or Transport) I get a huge sound stage. If I then change to a Sony CDP-997 (has a CD or transport) it does not give me that big of a sound stage.
I suspect you have identified your problem. The Sony, which appears to be vintage(?), has a poor or out of spec clocking system, and is creating a lot of jitter in the signal sent to the DAC. I plugged in my old Nakamichi CD player a few years ago to see how it sounded, unlistenable compared to the streamer I had in place. There could of course be other factors influencing the digital output of the Sony, but just letting you know what I have found experimenting with various digital sources running to the same DAC.