You can just wire directly form one to the other, positive to positive and negative to negative, no extra amp required as you will set it up with a SPL meter and the center channel will be louder than the rest initially and then you end up dropping the output a little in the receiver.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70