I would like to replace my 10 year-old dual LNB round dish with a newer one. Haven't decided yet if I want to go with the 3 LNB 18" or the 22.5-inch Ka/Ku dish for future upgrade to HD. I currently use a multiswitch from the two coax lines to feed two DirecTivos. From what I have read, both of these oval dishes have internal multiswitches which output four identical signals. Is it possible to use my existing 2-wire coax with one of these new dishes by hooking only 2 of the 4 outputs to my existing multiswitch? Or do I still have to use all 4 of the outputs? The dish instructions are not clear on this point.