long RCA cables . . .where?

Because I need to relocate my TT, I have to use aprox. 20ft of RCA cable to connect it to the preamp. I have two options here: one, run this long cable between the connectors from the TT arm to the MC amp, and second, use the longer cable between the MC amp to my preamp. What dou you consider would be better? and, could the signal be deteriorated in some form with 20ft of cable?. thanks in advance.