Subwoofer Options With No Spare Preout

I appreciate all the feedback this far. I do really like the idea of high passing my little Totems. This way I could set the crossover point higher. I love the Arros but obviously lacking on the lower end, probably even above 80hz. The Rels I still can’t let go of as an option because they are so well liked and reviewed.  Im guessing either way I could get good results. Figuring out which is best seems tough to do short of trying both though.  
 

anybody have any thoughts on the Sublime Acoustics crossover?  I like that it would eliminate the rca splitter. Also, I like that’s it’s affordable to try different crossover frequencies to see which I prefer. I worry I may need some sort of DSP though to get control of all the extra bass produced. Something like a mini dsp would be perfect but I just can’t believe it would t degrade the sound considerably. Thinking maybe a streamer that has some eq along with the Sublime crossover may be the ticket. My Auralic in my other system does have if I remember right a 5 band eq, and you can choose the frequency point which is nice. I feel this could at least get rid of any large peaks. 
 

Again thanks for everybody feedback!  

That website is a rambling mix of useful information and total BS I’m afraid.

Subs have significant output into the mids

BS. Not if properly configured. Most use a 4th order low pass filter and usually don’t go any higher than ~ 120 to 150 Hz.

and are localizable.

If you mean you can hear where they are there are only two reasons I know of only two reasons for this:

1. External vibration/rattling
2. Too high a crossover point.

In my system not only can you not localize the sub but you can’t even really tell it’s working until it is off.

Therefore they must be coherent with the mains.

No, eliminating localization and making sure your stereo output presents one coherent presentation are not exactly the same thing.

The easiest way to achieve this is to have them in the same area as the mains.

A - Not true and B - I wish it was that easy.

I know nothing but in a 9x11 room where will the 2 subs' waves go?  Seems  challenging

that stuff is elaborate....

https://www.hunecke.de/en/calculators/loudspeakers.html

from you sub link

Pass on the RELs as they do not have sufficient controls to integrate properly. IMO REL now markets bling as opposed to decades back when they were excellent.

Required controls are continuously variable XO frequency, variable XO slopes, continuous phase and polarity inversion. Without these controls only physical movement of the sub enables proper integration. Martin-Logan X series have the requisite controls.

It’s simple to build a HP xover for the mains which enables proper integration. Rolling the bottom octave out of the mains effectively increases main amplifier power.

Subs have significant output into the mids and are localizable. Therefore they must be coherent with the mains. The easiest way to achieve this is to have them in the same area as the mains.

See ieLogical SubterraneanHomesickBlues for more information on sub integration

Oh, the Duelund JDM-Cu are a steal at around $30 each from Parts Connexion.

I like the REL's very much and second jjss49 suggestion.

Hi OP:

The cap provides a first order high pass filter. You want to use a cap which provides the same impedance as your amp’s input impedance. So if the amp is 47k your cap should also be 47k at the crossover point, which I recommend no lower than 80 Hz. With those low efficiency speakers this will greatly reduce distortion and make your amp play much louder.

I believe this just happens to be 0.047 uF for you. I recommend Jupiter copper foils.

This simplifies subwoofer integration, and will double the apparent size of your amps. Also, most people report greatly improved soundstage and reduced distortion this way.

PS - There is a myth audiophiles have that they should buy a subwoofer only for 1 octave.  Every single time I've convinced those audiophiles to try the alternative they never go back, not just for the bass but for the overall improvement in detail, soundstage, and dynamic range.

op - a little repetitive, but uncle paul covers the topic you are wondering about

https://www.youtube.com/watch?v=lTZEMLCddh4

https://www.youtube.com/watch?v=5LW3dELp_Zc

https://www.youtube.com/watch?v=fD6VtaNbUCg

https://www.youtube.com/watch?v=5AoiS_e8wBA

https://youtu.be/hogWfVTpx_g

Erik can you explain why a cap and how you implement exactly? 

Y adapter from preamp.  Single cap in series with amps.

rel subs using amplifier speaker outputs for their high level connection

it is the better way to do it anyways

https://rel.net/blog/2021-02-09/system-thinking/what-is-a-high-level-cable/