Full range tower speakers with bass under $10k

I don’t think there is anything wrong with your speakers or your subwoofer.

Doesn’t your integrated amplifier have preamplifier outputs? What brand and model is it?

JL Audio states that using the E-Series high level (speaker) inputs for receivers and integrated amplifiers without line level outputs is not the desirable method.  

Full Range Passive Speaker.
Even the best are down 3dB just when most rooms need boost in that region, unless that's acceptable.

Full Range w / Internal Powered Sub.
Now you've got the ability to boost but the sub / room location is far from optimal and may actually increase room nodes, unless that's acceptable.

How about $7K speakers which are flat to 55Hz and two small subs with on board room optimization. The advantages of independent positioning and subwoofers with on board room optimization will dramatically reduce the rooms nodes while loading the room with what will seem like a tighter quicker bass response optimized for unnoticeable system integration. Real controlled full range presentation with subwoofers you'll use with any future speaker choice.   

skimrn OP6 posts01-01-2019 8:48pm@m-db, My amp is Marantz PM-10, it does have "Power Amp In" for Preamp, would that work? I thought I needed an "Out" for sending signal to the powered sub L&R. 
BTW, the PSB 3Ts does look nice!

Skimrn, Looking at the Marantz PM-10 manual, page 5 shows the rear panel item 2 "AUDIO OUT".  This output is labeled (RECORDER) output which usually outputs the full (all the way turned up) signal. Try connecting these L&R RCA connections to the subwoofer with the subs volume turned almost off then slowly increase the volume.

If this works for the subwoofer you can purchase a pair of affordable long RCA cables from MonoPrice or Blue Jeans cable to locate your sub anywhere in your room.