Do I need a sub?

Amp output red and white both into the audioadvosir connector
and into the single rca of the sub?

@jtcf ,

main out rca’s from preamp into the audioquest hard Y adapter..then into the single rca input of the sub?

this is all?

 How will this hookup remove the low frequencies from the main towers,???

would it sound better to just use the speaker wire hookup style, which will actually remove the low frequencies from the towers?

or will hooking up with the hard Y adapter also remove the low frequencies from the towers?

 Thank you , in advance for all your time guys.

Get a adapter w two male 1 female , plug adapter in back of main out of preamp, then run single shielded rca to sub?

easier this way? this will just dump everything over a certain freq to sub?

 Or use the speaker terminals which will remove the low freq going to the speakers (towers) and allow a little louder volume,by not sending lower freq to the smalldual 6” woofers???

You need a sub with a high pass filter. With that BIC V 1020 you will have to run your speakers full range!

Get one or two used RELs (or a swarm system if you have the space as they're alleged to work) and don't bother with the silliness of limiting the output to the main speakers and just 'em run within their limits. I used a single REL Q150e (10" front firing 150 watts) for a couple of years bought for 200 bucks (used of course...Ebay)...still works perfectly, and added a REL Q108MKII (100 watts down firing 8") later...also 200 bucks. You don't need to do anything but hook 'em to the amp's speaker jacks, and move them around until they sound good to you (putting one in your listening seat is unnecessary, and takes some long cables). Note that good subs add air to the proceedings by sort of "charging" the room and make even bass shy stuff simply sound like real music...it's not just about organ bass notes and EDM (although hey...).