I've seen other questions and answers here on choosing resistance values for potentiometers in audio circuits (headphones, speakers, amps, etc.) and have heard of a "4 to 10 x's the target load" rule, but continually hear people suggest values between 50 and 100K ohms, and have become confused because the impedances and location of the pot in the circuit vary so much.
I'm hoping for a fairly straight ahead answer: I have an amp that delivers 30W to each of the two (2) channels. Each channel contains a crossover composed of a 6 ohm and a 4 ohm speaker in parallel with each other. I can draw this full circuit out, or provide more amp specs if necessary.
To add a simple volume knob between the source (a phone or ipod) and the input jack of the amp, what is the logical process for determining a resistance value, and type (Lin/Log)?