Its not done yet but I can hit you back with the design and reports of how it works when I get them.
.. More to come.
Thank you, greatly appreciated!!
It is a voltage divider that erik_squires referring to:
https://www.crutchfield.com/p_543ADP12/Russound-ADP-1-2-Speaker-level-to-Line-level-Adapter.html?tp=...
attenuation: -30 dB, should be safe to connect to your subwoofer.
Thanks, will try this out and see how it goes!!
Thank you all for your help!!