High level speaker amp out to RCA

I have read many conflicting opinions on this topic, and the point you raise about introducing the amp distortion to the sub signal is very logical.bdp24 

I am having some issues with my RCA connection from my preamp. I hear the sub "interacting" with the speakers.  Sometimes it makes a clicking sound, other times there is a little click sound when I use the volume on the remote, up or down. Sometimes just straight interference sound, very rarely though.

My preamp is a Sunfire Vacuum Tube Controller, it has 2 parallel main out RCA style, and one XLR.  My amp, a Sunfire 300 Two, is connected with the XLR.  My sub/s, tried with single and dual, are connected using the parallel main out posts from the preamp.  The main idea was to go straight to the amp because apparently the Preamp is getting this interference. Just trying something new!!

Seems like its not that straight forward.  I there an external adapter/converter that is just plug and play??

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!!