with two D1s you'd be at .25 or 1ohm.
If you simply took all the positives and ran them to the amp and all the negatives and ran them to the amp( to their respective terminal of course) then it would be .25ohm
This is called wiring in parallel.
If you took a positive and connected it to a negative from the opposite set of terminals on EACH sub and then took the set of wires you had left and ran them to their respective terminals on the amp then you'd be at 1ohm.
This is called wiring in Series/Parallel.
If you simply took all the positives and ran them to the amp and all the negatives and ran them to the amp( to their respective terminal of course) then it would be .25ohm
This is called wiring in parallel.
If you took a positive and connected it to a negative from the opposite set of terminals on EACH sub and then took the set of wires you had left and ran them to their respective terminals on the amp then you'd be at 1ohm.
This is called wiring in Series/Parallel.