The simple answer to this question is, there is no simple answer. The sound quality of one hook-up compared to another depends on many variables. The quality of your amp, the quality and bass performance of your amp, the room interaction with your main speakers, sub. It all boils down to what sounds best to you in your circumstance. I use a REL sub with an ARC amp and employ the high impedence input driven by the speaker output from the amp. Try all posibilities and see(hear) what sounds best. Do not settle on the crossover freq. yet until you have experience with your room. Some speakers have more bass than their specs would seem to indicate. Some less. Above all have fun!

Jim