Topband: Beverage feeding

[Stein Roar LA6FJA-K3RAG]

Hi 

I wonder how much difference it is if I have antenna switch for different RX Antennas in the field with 300 ft. 50 ohm coax, and then I take a 300 ft 75 ohm to my beverage feeding box from DX Engineering....

Does this change of coax impedance mess up the RX signal even I use a preamp ??? Or should I go straight with 75 ohm from the shack down to the switch.???

73 LA6FJA Rag