Has anyone tried replacing SMPS (Switched Mode Power Supply) inside ADI-642 by LPS (Linear Power Supply)?
If someone from RME is reading this, could you please comment if it is advisable to do so and if there are any benefits in doing that? If not, how is noise associated with SMPSs have been addressed inside ADI-642?
This question does not arise here at all. The device does neither A/D nor D/A conversion. It works on a purely digital basis and converts digital audio data (zeroes and ones) from one digital format to another (MADI->AES and vice versa).
Furthermore, AES and MADI (optical) provide galvanic isolation between devices, see e.g., https://forum.rme-audio.de/viewtopic.php?id=16886.
Regarding other RME devices which perform A/D and D/A conversion. The devices achieve the excellent and documented technical specs with the PSU that is provided with the device. This is fully sufficient.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13