UPDATE: tonight automagically my Volumio v2.853 on the ASUS Tinker Board worked again without issues. I have reproduced an album sampled at 192/16, another at DSD128 and finally a third one at 48/16. In all cases not a single glitch, or stuttering.
The only notable thing that has happened is that I have left the Tinker Board switched on for the whole day. Maybe some background operations got completed and are no longer interfering with the music reproduction? I don’t have any other explanation. Glad it is working again.