zapco ST-2X SQ Owner's Manual page 16

Using the built-in active crossovers of the ST-4X SQ, you can easily create an active
2-way system with mid/highs on the front channels and bass on the rear channels.
Below is an active system with a bridged subwoofer on the rear channels.
The 5-speakers system requires a passive crossover between the front highs and
the mono woofer, with capacitors on the front highs positives and a coil on the
woofer positive. All amplifiers channels are full range.
Bass 4Ω Min
14
2-way Active System
5Ch System
Highs 2Ω Min
Mono Bass 4Ω Min
Highs 2Ω Min