Digital optical To RCA and HDMI to RCA

Mar 12, 2018
i have home theatre 5.1 surround system of sony which has only RCA input and no HDMI /coaxial/optical digital input sockets. ( it has only HDMI output for its dvd )
my question is digital optical output if converted to RCA by a converter , will it give better audio dolby digital surround sound than current RCA cable

second question is howbto convert HDMI dvd out put to RCA inpit to home theatre and will it give better AV quality?