I have a 27" iMac with Thunderbolt port, and this work great as both an independent desktop and a larger monitor for my MacBook Pro. Now I need to use the iMac to display streaming from my Roku player, which only has an s-video out (and optical audio to my Home Theater system). I'd like to hook up the Roku to display video on the large iMac, but see no such adapter cables for s-video to Thunderbolt. Would I be better getting a new Roku or Apple TV (HDMI out), or abandon Roku and view programs directly on iMac? My Home Theatre system can also accept an aux cable for sound out from the iMac. Thanks.