Magnepan MG-10 and a Sub

Is it best to hook the subwoofer to the speaker, then into the hi-level in connection on the subwoofer?  Paul McGowan from PS audio says its better than using RCA connections from the pre-amp.  

Second part of my question is, on the MG-10 there are 3 pairs of speaker connections:

Speaker + -
Tweeter Attenuator (has a jumper inserted)
Low Frequency Roll-off (has a jumper inserted)

Should I hook the sub parallel with the speaker inputs, or remove the Low Frequency Roll-off jumper and hook the sub in there?