the LFE input is the simplest connection. It should bypass the sub's x-over because the receiver will be handling that. Using this input, it should not matter where the x-over is set on the sub, but it would normally be set to its highest point (150) because the receiver is handling the x-over. The R&L inputs are for use with system that are generally 2ch only and have NO sub output. The R&L inputs are summed to mono anyway, so the only difference would be that the crossover on the sub is used with them. Unless your sub is on the opposite side of the room from your main speakers, the phase should be set to 0.