Both of those resistances are trivial. Looking at high frequency rolloff as a result of output resistance, suppose we have an output resistor of 7,950 ohms and we assume a total cable capacitance of 100pF. That would give a -3dB point at around 200kHz. If the input impedance of the amplifier was also 7,950 ohms (unlikely that low), then the gain loss would be -6dB.
Believe me, working at the sausage factory as I do, there are a lot more ugly things to obsess about than buildout resistors, and that is true of all sausage factories (uh, manufacturers)!