My sub experience was very easy. Put the 2 (custom 18") subs in the corners where they belong (MUCH easier said than done - very heavy.) Hooked up the amps to the subs (one per sub), connected the crossover / LP filter to the amps, connected separate cables from the preamp to the crossover. Fired up the preamp and rest of the system. Fired up the crossover, then the amps. Played some music with REAL bass - Saint-Saens, Ravel, Respighi, Stravinski... Adjusted the crossover level as the music played. All good. Done.
Done.