Long distance between preamp and power amp

Thank goodness we have Al, the voice of reason. Getting rid of that amp just to change the mode of connection would be ridiculous. 

Thank you all for your inputs. I will definitely keep the amplifier, so the bottom line is I will run a good pair of RCA cables inside a shielded sleeve and under my floor - I believe I'll be safe from interferences. 
I work in a theater where we have all sort of professional grade cables (including underwater cables). I'm sure I'll find a good quality cable to perform this task. And as I said, it will be a temporary solution. 

The problem with long RCA interconnects is a loss of high frequencies and definition.

The way to deal with it is run balanced connections to the amp and convert from balanced to single-ended using the Jensen transformers Al suggested earlier. That way works!