Sub wiring help, high level speaker terminal to RCA line level Sub inputs

Wanted to post a follow up. I've spoken to all 3 companies in the mix, Rythmic, Cambridge Audio, and Schiit, they all said to use the RCA line out with a Y splitter.

This is what you call CYA. Both methods are at best the same. Both methods run the risk of introducing a bit of distortion. Think about it. But the distortion of the LOC affects only the bit going to the sub, and is simply never going to be heard. (Done it, so experience here not opinion.) With the Y however then whatever distortion it makes goes right into the amp and comes right out the most high resolution high hearing sensitivity part of the system. Not taking sides just let's be clear. Its so true, already you are asking what is the best part to use. Whereas with the LOC it just doesn't even matter.

Where the CYA comes in is even though its definitely not the best way to go SQ-wise, it is definitely the lowest risk of customer screwup. Which people think businesses mostly try and make good stuff. When really the hardest part of all is making stuff their customers can't screw up.

A Y-splitter coming out of the pre-amp to connect the amp and the sub will probably work just fine. Doing it that way the pre-amp will see the input impedance of the sub and amp. Where now it sees only the amp. Should not matter but not knowing any of those its impossible to know in advance. The bigger concern I would have, and still not much but it is bigger, is this puts a splitter in the signal path to the amp. More to the point, it puts an additional connection in the signal path. No matter how high quality a splitter you get, or how great the connection, there simply is no getting around the fact you're degrading the signal. Whereas using the power amp speaker path leaves your signal path pristine, untouched.

Frankly this is probably more a theoretical than practical concern. In all reality you will probably never hear the difference. But it will be there. That for me is enough to not even want to try, and is why I suggested the LOC instead.

Here is the actual LOC circuit along with a very succinct explanation
http://www.epanorama.net/circuits/speaker_to_line.html

Study it. This is exactly what I did. It was worth it to me to install this circuit- really nothing more than 2 resistors and one short length of wire per channel- inside my amp. It is however a very simple circuit. Keep in mind it does not matter at all where this circuit is located. When you buy a sub with speaker level inputs the exact same circuit will be used only inside the sub. 

Also like the above link explains these are 1/4 watt resistors. They can be so small because hardly any power goes through them. Regardless of volume. Regardless of your amps power. Regardless of how much you turn it up. The difference between one LOC made for high power and one for lower power is not the resistor wattage. Its the resistor value. The 10k resistor isn't used to pass power. Its used to attenuate. A bigger amp would use a 20k or greater resistor, but it would be the same 1/4 watt value.

What this means, being so small, no heat output, you can put it anywhere. You could practically wire it into an interconnect if you wanted.

Also the parts are like $2. Total. Quality just does not matter. It might if you were using it to listen to the full range signal. In this case though, low bass only, waste of money.

How you do this depends on a lot of things I just can't know. What you like the looks of, for example. What interconnects you're using. What you may or may not be comfortable soldering or modding. You could for example very easily remove the RCA from the end of one interconnect, solder the resistors, and attach the wires at the end to your amps speaker binding posts. Direct from the speaker outs to your RCA ins.

That one link above, just the one page, contains a wealth of information. You just have to figure out your best way of making use of it. I did, and mine works and looks just as good as any professionally built component. Yours can too. You just have to decide how you want to do it. Heluva lot less work than boxing and shipping. Lot more satisfying too.

IMO, using high level input connectors offers the best possible integration with your mains speakers.

Okay so here's the thing. If you look at the schematic for subs with high level input connectors, the circuit is exactly the same as the LOC described above. Exact. Same.Thing.

The only difference is the circuit is inside the sub, as opposed to being in the LOC. But wherever it is located, it is the exact same thing.

rhern213, sorry for the bad advice above. I've actually done this. The simplest solution is a Line Out Converter or LOC 
https://www.parts-express.com/stinger-sgn111-30-watt-fixed-line-out-converter--268-482

This is simply a couple of resistors between the wire inputs and RCA outputs. One resistor drops the amplifiers output voltage down to line level, the other provides the impedance load to whatever the output component needs- the sub in your case.

My integrated amp didn't have a pre-out and so when my new sub amp had like yours only line-level inputs I researched this to death before modding my amp. In my case I am comfortable modding and installed the parts inside my amp. It does look better that way. Electrically however it is identical to the above LOC, which I'm sure you will find a whole lot easier to use.