[avahifi]

A client suggested the following.

Get a 1/4” stereo phone plug. Connect two coax cables terminated with male RCA plugs. Connect from headphone output on the control amp to the subwoofer    line level inputs. Adjust woofer volume to match main speakers.

A better solution is this:

https://www.showmecables.com/1-4-in-stereo-male-to-dual-rca-female-adapter?utm_id=361522565&keyword=&msclkid=5b37b96147f21ab2cca3dd0ae8f0e8fc&utm_source=bing&utm_medium=cpc&utm_campaign=(ROI)%20Shopping%20-%20Numbers&utm_term=4577266909614369&utm_content=Adapters

Instant set of line level outputs!

Frank

[TomBo]

Frank,
Very smart suggestion and it solves a question I had too.  I will try this out. The headphone jack stays energized while listening through speakers! Now I see.
Thank you,
Tom

[Lazeez]

IF your subwoofer has high level inputs, you can use an extra stereo run of speaker cable from the amp to the Left and Right speaker cable inputs on your sub.  Then adjust the crossover in your sub.