Massive Audio Primo Series Manual page 10

Fig 7. PX4/PX4S/PX4R AMPLIFIER WIRING
(3-CHANNEL MODE)
2 OHM-4 OHM 2 OHM-4 OHM
4 OHM MIN BRIDGED
Fig 8. PX4/PX4S/PX4R AMPLIFIER WIRING
(4-CHANNEL MODE)
2 OHM-4 OHM 2 OHM-4 OHM
2 OHM-4 OHM 2 OHM-4 OHM
2 OHM MINIMUM STEREO
4 OHM-8 OHM