gordee first of all you the pre amp does not have a pass through so if you unplug the power it wont work properly.
The pre amp has to be plugged in or completely removed from the setup.
If all your signals are down with the preamp then yes you are over driving the samsung receiver.
You can either remove the preamp or add some attentuation to the signal maybe 6 to 9 db.
Because of your location you maybe in a valley/lower elevation and that is causing problems with Nbc & Fox.
Most of us that lives north of the Cn Tower and in the gta you have to point the antenna more south east to get a max signal from Nbc. You have to compromise between Sun and Nbc.
The antenna needs to be pointed west for Sun and south east for Nbc. If you can get these two stations in good strength then your antenna is aligned properly.
Where you installed your antenna is the view clear pointing south ? Where do you have your antenna mounted ?
CM4228/9521/7775;F.RmJvc70FH96/8300HDPvr/Dish 612;B.Rm LC52LE810UN/8642HD;Study LG50PK550/Xbox360;