TV / Cable System Upgrades

The quick answer is NO, just a splitter will not work like you are talking about, and you already have one installed. For the rest of it, What you have is about the best you can do, although some upgrades will probably help. Change the batwing head to a newer Sensar IV, or a Jack, either one will be a 10 min replacement and the new ones are a lot better. The cable wall plate is an AB switch, to switch between cable input and the antenna. It also supplies the required 12v to the antenna head amplifier, which is located up in the antenna head. The three connections are cable in, antenna in, and TV out, plus a 12v power. It may or may not be good, replacement would not be a bad idea, but get the Sensar amplified one, cost a bit more but really works well. You also need to check all the connectors, and may need to run a new cable from the Wall plate cable jack out to a more convenient location on the outside or in a basement. New, fancy, expensive systems installed in many new rigs are set up for TVs, DVDs, and surround sound systems, and can get quite complicated. The type you have will perform just a well and a lot cheaper. There is a lot more information available, and I am sure someone will post with a lot more details.