Originally Posted by Brian Kendig
Antenna -> Signal amplifier -> Through the walls to a cable junction box in the master bedroom closet -> Splitter
if you didn't want to swap the premieres as first step, instead of attacking the wiring from the living room end, there is another approach.
you could temporarily replace the splitter in the bedroom closet with one of the attached - Barrel Joiner Connector Coupler - whatever you want to call it. that would direct all the signal to the living room instead of having the splitter drop the signal 3.5db on each leg of the split. that's a quick and dirty test to see if that gets you channels 2 and 6 and would confirm a signal level issue.
And then if that works and you don't want to attack the "spider web" of cables going to living room, to complete the quick and dirty fix, you may be able to get away with a directional tap to split the signal - see attached. where the -6db leg goes to the bedroom on the shorter run and the other leg goes to the living room, directing stronger signal on that path. might be enough to get you over the hump. The directional splitter isn't a bad idea either way as it's only a few dollars and will direct more signal to your longer length run to living room. may need to clean up the spider web run to the living room anyway to boost the signal more, but installing those should be easy if the closet splitter is easy to get to. sounds like the living room wiring may be buried behind an entertainment center or something and a challenge to deal with.
but you could have a bad connector or a crimped cable in that living room run that is attenuating the signal that is the real issue. but the method above might be a quick band aid to apply until you root out the real issue. and it's not a wasted step since I'd leave that directional splitter there. and btw, your amp, does that have a single output to the splitter? it's not a multi output splitter is it? because that would split and drop the signal as well if there are unused ports.