1) Have you fed yr room dimensions into a room modes s/ware to see where nulls are (try Rives' site)?
2) Try positioning the spkrs @ 1/4 the way into the room
3) Check spkrs' internal polarity as suggested; use a small battery, the + pole should push the woof outwards.
4) Check the subs' amp sensitivity vs the Mac. You may need to adjust.
4) Finally, to get the wire issue out of the way, try zip, or any cheap single core wire available, as spkr cable. Unlikely, but you never know.
2) Try positioning the spkrs @ 1/4 the way into the room
3) Check spkrs' internal polarity as suggested; use a small battery, the + pole should push the woof outwards.
4) Check the subs' amp sensitivity vs the Mac. You may need to adjust.
4) Finally, to get the wire issue out of the way, try zip, or any cheap single core wire available, as spkr cable. Unlikely, but you never know.