Which Roku? Will they use the TV to navigate? If so, analog RCA will work, or you could use a small DAC, which can receive either Optical or Digital Coax input to convert to analog. Gefen, Key Digital (I think) and others sell these. I have bought them from Skywalker and they seem to be the same as Gefen, Vanco, etc. I keep at least one in my van at all times and they're not expensive. I have no complaints about the sound quality.