Question on Fisher 500C

Finally, got a 500c working and in good order/shape at this point I have zero complaints with the unit. I have been thinking of down sizing the speaker setup and going with a sat/sub setup. The question I have that I cannot seem to find good info on is the pre-out on the Fisher. Anyone working this with a sub. I assume rca out to sub and back in to amp to complete the circuit, but was not certain if/how the pre out will work if I cross over via the sub and bring it back into the amp. I am guessing I can use the speaker terminals to get to the same thing, but again not certain what effect that might have on the sound of the fisher. The top/mid is just perfect, but would like to go smaller without loosing the bottom end.

Any help of suggestions?
Running the whole signal through the sub crossover will probably degrade the sound a little. If you could run the sub from the pre out and run the sats from the R&L outs it may sound better. You would then just need to play with the crossover level on the sub to even out the bass.