I read the owner's manual and found that the NR1608 supports playing back DSD 2.8/5.6 MHz files saved on a PC or NAS or USB memory device but not SACD, not in DSD direct mode. I don't know what you meant by "the tv screen said "DSD 2 ch 2.8 MHz/1 bit....". Perhaps it tried for a short while, couldn't do it and switched to PCM.
The lowest/oldest 2018 D&M models that support Super audio playback via HDMI in DSD direct seem to be the AVR-X3200W and SR6010.