If I understand correctly a recent presentation by Eli Ben-Sasson, one of ZCash's scientists, there is now at least one ZK system with this 'transparent' proper

If I understand correctly a recent presentation by Eli Ben-Sasson, one of ZCash's scientists, there is now at least one ZK system with this 'transparent' property (needing no trusted setup), but it is not yet practical for a blockchain currency. See Ben-Sasson on "STARK": https://www.youtube.com/watch?v=HJ9K_o-RRSY https://www.youtube.com/watch?v=HJ9K_o-RRSY