JL Audio d110 vs e110

The D110 has no high pass filter. You need to run the main speakers full range! Which is fine if that is all you need!

that is all I need...it seems the specs are only slightly different, though the e has more power and goes a little lower. but maybe not in real world application...

It just so happens that I am selling a mint D110 on Audiogon as we speak!

Did you also listen to the e110 ?

No I have not. I like running my mains full range so there is no reason that I would need a sub with a high pass filter option! My friend uses the E110 with Proacs and he does not use the high pass filter. Why pay for something that you will not use?

It keeps the deep bass frequencies out of the main speakers. Which can help The main speakers and amp sound better.  But can also add distortions.  

So depending on system,room, preferences, many options and debate 

On many subs the high pass filter is fixed at 80 HZ!

it has a crossover network inside. cables go from preamp to subwoofer, then from subwoofer to amp. amp only gets non deep bass signals to send to main speakers.  therefore main speakers get signal from sub's crossover, not always a good thing.  proper set up of sub can be quite difficult, some say impossible... 

and then there can be all kinds of settings and placement...

but can be fun too

The jl e110 manual is available online.  Lots of information and full set up instructions 

d2girls, not all subwoofers have the same features and connectivity options. Your Pass Labs preamplifier has at least two Line Level preamp outputs RCA and XLR. Most subwoofers can accommodate RCA connection others can accommodate both. You get what you pay for. 

Not all subwoofers with high pass filtering degrade the signal to the main speakers. Again, you get what you pay for.

One brand suggests using their high level connection (amplifier speaker cable to the sub and a speaker cable from the sub to your main speakers). In a direct in home comparison we found this connectivity to noticeably interfere with my main speakers sound staging.     

Subwoofer digital signal processing (DSP) design is usually somewhat different from one brand to another. Once again, you get what you pay for.

From reading your posts your main concern seems to be getting good integration with your system which includes your room which is why most DSP systems use a calibrated microphone that determines the particular systems different parameter/s of adjustment. Here again, you get what you pay for.

If you get a sub on a trial basis as I suggested earlier begin with this. Disregard the home theater aspect this works for two channel too. Connect a long cheap RCA cable to either L or R preamp output to the subs input.
https://www.youtube.com/watch?v=R4o13mNmlaA

If you will need a pair of these if you use a sub without the high pass option!
https://www.audioadvisor.com/prodinfo.asp?number=AQM22FHRD