Ron, welcome. Your description isn't entirely clear as to what you intend, and you mention both line level and speaker wire. Although 75 feet is longer than recommended for 16ga, this is for background music and a direct connection to the remote speakers from the B terminals of your receiver shouldn't degrade the sound too significantly. However, most of what you discuss concerns interconnects(rather than 16ga speaker wires), presumably from preouts in your living room to remote amps. Relatively inexpensive "RCA" type connects are available even for such a long run and should be adequate if interference levels in your home aren't unusually high. Again though, you should describe the setup in more detail.
