Connection only subwoofers NX3000D, doubt

Hi all : I bought the Behringer NX3000D amplifier several days ago and still haven't connected it because it was difficult for me to get the SpeakOn connectors. The use I'll give you is exclusively to power two passive subwoofers of 18 "each, in a home system.The satellite speakers are powered by a valve amplifier. I have read the manual but I have not found an outline or explanation about which SpeakOn connector contacts to use in my case. The idea is to control the sub-frequency range with the built-in crossover, and the other functions like time delay and phases. Should I use 1+ and 1- or 2+ and 2- ?
Can you please clarify this?
Thank you