Not a teacher
I think the sentence is OK. He says:
“There’s something in his voice and my voice that are so different—I’ve got the name in my head already, Silk and Sand.”
In my opinion, what he wants to say is: our voices are totally different but there is something (special) about each of them; my voice is harsh (like the sand) while his voice is soft (like the silk). Though he seems to use the title Silk and Sand in an ironical way.
That is the impression the text makes on me.
Student or Learner