Mcintosh int amp MA6600 used as power or pre-amp?

I want to use my Mac int amp MA6600 in a power & pre-amp set up and buy some Mac, Simaudio or Classe amp/pre-amp. Should I use my MA6600 as power or pre-amp or even bi-amping?

Is the power amp part better than the pre-amp part in my MA6600 or the other way around. Generally speaking, is pre-amp affect the sound more than the power amp?
I use my MA6600 as a power amp with my Mc tube C220 preamp to get the tube sound. I switch the setup back and forth and enjoy both. I think you are better off using it as a power amp and you can try differnet sound with different preamps (including different brands).