What ohm rating is this amp at and what sub is needed

[i9z4real@yahoo.com 0]

I've got a crescendo 1000c4 that can run either 500w x2 bridged at 4 ohms

250w x2 bridged at 8 ohms

 

 

how can i tell if its wired at 4 or 8 ohms ?

 

and if it was at 4 ohms would an s4 sub work ? or only d4

[jonbearsmt 919]

 the best way i with a Digital multi meter,

 

  a single 4 a dual 8 a dual 2  are all options with a single sub