Another subwoofer connection question

I’ve looked at similar threads but feel I should get advice specific to my setup. If I wanted to connect my LM 518 integrated to a sub to augment Spatial M3 Turbo S’s, would I just run another set of speaker cables from the LM’s taps to the subs speaker inputs? Or is that going to mess up the LM? The Spatials use the 4 ohm tap; would I run the other set of speaker cables from the 8 or 16 ohm tap?
The sub in question is an ancient (2003) Velodyne CHT-8