In the world of Digital TV, signals can act very different from the old days. Desert Hot Springs is able to get some LA channels through the Pass, due to signal bounce and weather. Clear and colder weather will allow some digital signals to travel further. BUT, warmer/stormy, forget it.
Even if one channel broadcasts on lower power... with digital, most of the time watts don't matter, its the channel assignment, weather and direction of your antenna.
If I were in DHS, I would play around with my antenna's to see what I can get, but I wouldn't invest any large sums of money in pre-amps, or antennas. There are too many factors to keep out a regular signal from LA.