Run the RCA to the Minidsp and use it for sub integration.
JL Audio make a active speaker level to line output converter LoC-22
Jensn Transformers also offer a passive speaker to line level converter
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.
Before the Jensen SP-2SX arrive, I suggest you take a moment go through the manual and see if you have any questions about the installation and also get all cables that required.
Thanks for the help, I reviewed and printed out that document.
Interesting, that it prefers shorter Balanced (XLR) output cables and longer input speaker cables.
I did order the Neutrik Speakon plug to attach to a set of speaker cables. But, there is also screw terminals in the back of the unit if one doesn’t use the Speakon plug.
I should have it tomorrow or Wednesday with return rights within 30 days if it doesn’t do it for me.
Ozzy, Any detriment additional processing might do, particularly digital processing will be made up for 10 times by the decrease in distortion to the main speakers and improvement in integration that a dedicated crossover allows. If you come off your streamer with a digital output to the digital input of the crossover you remain in numbers where there is no distortion at all. You just do your conversion to analog after the crossover instead of after the streamer. The way you are headed is the worst way to go but it is inexpensive and we are all entitled to make our own mistakes.
Well I got the (2) Jensen Iso Max SP-2SX today.
I used a balanced 1/2M Wireworld Platinum Eclipse 8 to keep the XLR connections short as per the instructions.
First listen, everything seems to works fine, no hum, all (4) JL F-113 subs are working, but I will have to listen more intently to be sure and perhaps recalibrate the F-113’s.
I am really digging the seamless integration, everything sounds great! I don’t even have to recalibrate the JL- F113’s.
For those of you without subwoofer outs ( most of 2 channels folks) or use tube amps and want to add subs, this is the ticket.
The only negative is Jensen never replied to my emails, and I even left several phone messages. I even talked to a lady who said she would forward my message and still no reply. Not a good way to do business in my opinion.
But again, I can highly recommend this approach to adding subs to a system.