Depends on if you want tor wire them in parallel @8OHMs 4 OHMs or 1 OHM
or put them on a 2 channel amplfiier and wire each to either 8 OHMs 4 OHMs 2 OHMs or 1 ohm
i would suggest finding an amplifier that will power them each on their own channels @ 2 OHMS so 400x2@2OHMS
for your cheapest option because i will NEVER suggest 1 OHM... its an amplifier killer