Is there anyway to convert a JL Sub to connect to Main speakers?


I am thinking of going straight from a Lumin X1 Dac/Streamer etc. directly to my main mono block amps, thus eliminating a preamp. I was very impressed with the purity of the sound  from the Lumin when running direct like this. However, I would like to incorporate my subs.

I have been told by Lumin that using the line level outs (XLR) for the main amps and the (RCA) outs for my subs at the same time will result in not so good of sound. I tried it, and though it works, the sound is not as pure as just using the one set of outputs for my mains.

Lumin suggested using Rel subs connected to the speakers/amps using the high level speaker connection.
But, I already own 4 JL Audio F-113 subs that only accept line (low) level connections.

Question:
Is there some type of converter that can adapt a line level input  from the sub to connect to the high level speakers?
Sort of like converting my JL Subs to the Rel design.

ozzy
128x128ozzy
JL Audio make a active speaker level to line output converter LoC-22

https://www.jlaudio.com/products/loc-22-car-audio-oem-integration-processors-98413

Jensn Transformers also offer a passive speaker to line level converter

https://www.jensen-transformers.com/product/sp-2sx/

Both can be work like the Rel subs connection method.

Amplifier speaker out > Converter > JL sub line-in
Ozzy, great subwoofers and 4 to boot. That is some serious low end potential.
The absolute best way to do this is to get a dedicated digital subwoofer crossover. You would take the digital output of your DAC and connect that to the digital input of the crossover which will work it's magic and give you analog outputs for satellite amps and subwoofer amps. The unit I like the best is the Behringer DCX 2496 https://www.parts-express.com/behringer-dcx2496-ultradrive-pro-digital-24-bit-96-khz-loudspeaker-man... Then there are the dbx units the 223xs and the Driverack PA2. The dbx units have analog inputs only. 
The Behringer will allow you to time and phase align the subs and it has a digital input (AES/EBU) 
JL Audio also makes a subwoofer crossover I believe it is entirely analog which is a serious weakness. Digital signal processing has far less distortion than analog. It also allows for signal delay which is how you align your system in time.
Yours are powered subs,

Preferably you want to keep the need for low bass out of both your main amp(s) and your main l/r speakers, so neither the amps or the mains try to amplify/reproduce low bass, they both will more easily do a great job for upper bass/mids/highs.

You need an adjustable crossover, either dedicated crossover near your streamer, or crossover built in the sub(s). Length of either rca cables or length of speaker wires help you decide.

my office, source rca to amp, a single 12" velodyne self powered sub, always on, speaker wires amp to sub, sub's internal adjustable crossover and volume, speaker wires from sub to bookshelf mains. So the amp is always still reproducing all the bass, but the bookshelf mains do not try to make low bass that they cannot do well.


Thank you all for the great suggestions. I'm going to review all of them.

I did first consider the JL Audio crossover. The main objective is that I do not want to introduce additional signal processing, for this would reduce the pureness of the Lumin X1 going direct to the amps.

So at this point I am going to stick with units that use coming off of the main speaker outputs into the subs.

ozzy