To me cydnabod means recognise in the sense of, say, recognising authority or responsibility. I would use adnabod or nabod for recognising (subtly different from knowing) a song. Your mileage may vary, though.
Diolch…i had written adnabod but got cold feet reading discussions online doh damia!
Acknowledge is the word I was looking for.
Al Lewis Trywydd Iawn
That’s Owen Powell’s son on bass, BTW.