connecting a sub to nad c-162 pre

I have a friend that just bought a emotiva ultra 10 sub.He can't figure out how to connect the sub to his NAD C-162 pre as he is already using both pre-outs for powered full range monitor speakers.(Mackie HR824)Anyone know if this can be done?I don't think it can as the emotiva sub has no line level inputs for full range/high pass speakers(as some live subs do)and there are no other pre or main outs on the NAD.
Unless your friend is running 2 pairs of mackies,he should have enough outputs. Pre out 1R (or 2, it shouldn't matter) to right speaker, pre-out 1L to left speaker. Pre-out 2R to sub R input and Pre-out 2L to sub L input. If he's running 4 speakers, he will need RCA Y cables (also called splitters).