I have an old TV with an analogue tuner and a Sony RDR HXD710 with a single digital tuner. When my area goes digital in April I will no longer be able to watch one channel and record another. Can I simply add a set top box to allow me to do this and if so how would I link up the TV, set top box and Sony recorder? Would I need to set up the set top box with the TV before linking in the recorder?