Dumb question regarding TV and my iMac. I have a Comcast cable screwed in to my modem, which has another cable going to my router. Can I simply put a splitter on that cable line (before the modem) and run the other wire to an elgato device? I don't have another wire in my room for cable television, the only one I have is used for internet and is connected to my modem. I am looking to get a eyetv tv tuner for my imac. Thank you for all the answers in advance. By the way I am subscribed to both cable tv as well as internet.