Thanks for your answers, then it seems a viable solution to be able to replace/complement the bad quality created by the RF cable passing through all that equipment [Linked Image from softronix.com]

The largest problem is to find a place where I can get the cables through to the seconfd floor, where the antenna cable is it's not even possible to fit a second antenna cable [Linked Image from softronix.com] - that's why I thought more of a splitter than two cable sets. The cable length will be similar since the two rooms with TV sets upstairs aren't that close.

HD621, G98DH, G68ADV, Bc Acoustiqe ACT A3, 5200C DSP33, NuForce Reference 9 monoblocks, 2x SB3's, Velodyne DD-15 & DD-12 Subwoofers and a Meridian sub.