What do i need to get 8 pres (full chasis)?

so i want to order 4 A12's an 4 N72's
as i understand i need to order 1 PS03 Power Supply + 1 CH01 chassis + 1 WH01 wiring harness with them?
only one wiring harness?
what is op-amp - do i need to order it too?
as i understand i need to order 1 PS03 Power Supply + 1 CH01 chassis + 1 WH01 wiring harness with them?
only one wiring harness?
what is op-amp - do i need to order it too?