Simaudio Moon 600i Sub?


I have a Simaudio Moon 600i integrated amp hooked up to a pair of Totem Tribe III towers. Does the Simaudio Moon 600i offer any means to connect to a subwoofer (or two)?? Any help would be so much appreciated.

I also want to point out I have a pair of Totem Tribe V speakers and a pair Focal Chorus 836W speakers and a pair of Genesis 5.3 loudspeakers that I am taking turns hooking up to the Moon amp. I want to tie in a sub! Please help :)
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They have a fixed preout with 600i. Have not tried it though. I am thinking about adding an external amp via the same preout. Curious also if anyone has had experience with this.