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


I just received a new Rhythmic L12 sub, and surprisingly did not realize it only has RCA line level inputs. I had purchased it thinking it also had high level speaker inputs to connect it directly to the speaker posts on my power amp.

I have a Cambridge CXNv2 connected to a Schiit Aegir Power Amp through the line level RCA. Now, the CXN does have an additional balanced XLR out, but I can only connect the Schiit Aegir through RCA.

So these are my options and questions:
1. Connect the Power Amp to the Sub using a custom cable with speaker terminals on one end and RCA on the other end.
2. CXN XLR --> Power Amp RCA, and CXN RCA --> Sub RCA
3. CXN RCA --> Power Amp RCA, and CXN XLR --> Sub RCA
4. Return the Rhythmic and get an SVS SB1000 with high level speaker inputs.

In this case I’m not sure what the positives and negatives are about trying to connect the Sub via speaker terminals or RCA line level on the CXN. Or is it even advisable to use a cable that goes from the speaker terminals to the RCA line level inputs of the Sub?

Appreciate any help!
rhern213
I completely agree, that's the main reason I didn't want to go with any kind of adapter/splitter and just figure out some way to get a direct connection. It bugs me to spend money on better speaker cables and then terminate them with a Y-splitter.

Just for discussion using the resistors, is it possible to get unwanted feedback back into the pre-amp that can cause some other kind of distortion?
Not sure I understand your question in the post just above. Regarding the first paragraph, a y-splitter would not be used to terminate the speaker cables. Regarding the second paragraph, the resistors would not be connected to the preamp.

In any event, the resistors themselves would not cause any kind of feedback into the power amp to which they would be connected, aside from what is known as Johnson noise which would almost certainly be audibly inconsequential in this situation. And in the unlikely event that the sub itself sent some sort of feedback to the power amp, that might have audible consequences as a result of being injected into the amp’s feedback loop (assuming the amp has a feedback loop), the presence of the resistors would reduce any such effects, not increase them. And likewise with respect to any RFI/EMI that may be picked up by whatever wiring is between the resistors and the sub.

Regards,
-- Al
@almarg I understand I meant terminate as just the end of the cable. You're right I miss-spoke saying pre-amp, I meant power amp. Thanks for the explanation!
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. They said the speaker post connection would at best sound the same, but have the side affect of potential distortion so there's no real point in using that connection unless the sub was made to use them.

I tried using the amps speaker post output anyway, the volume levels were not incredibly different, they were about 25% louder than the RCA line out. In the end I couldn't really notice any difference in sound quality between either one when volume matched. So I'm going to stick with the RCA line outs using a Y split for peace of mind.

Now I have one last question, I've been using BJC LC-1 cables to my power amp, but for now only had left over cheapo component video cables I was testing to the subwoofer. I would like to get RCA's that are Y split themselves to not have to use an added Y adapter. However BJC cannot make the LC-1 cables in Y configurations, only their MSA-1 cables which don't have the same gauge, shielding, etc..

So I'm not sure if it would be best now to use 2 higher quality LC-1 cables attached to the separate Y-adapter, or use 2 lesser quality MSA-1 cables already Y split and eliminate the use of the adapter.

Or is there another cable company that can make better quality custom Y cables for the same price as BJC?
LC-1 cables plus a pair of Audioquest splitters would be a much safer bet IMO than MSA-1 cables in a y-configuration, and the greater the length of the cables the more true that would be.

While there have been various reports and/or claims here to the effect that "splitters degrade the sound," my belief is that in most of those cases the reported findings result not from the splitter itself, but from some combination of impedance incompatibilities that can arise when a splitter is used; ground loop effects that can sometimes occur when an output is used to drive two separate components; and increased loading of outputs by cable capacitance, that can result when an output is split and is used to drive two lengthy cables.

I couldn’t find an output impedance spec on your streamer, or a spec on the capacitance of the MSA-1 cable. However given its small diameter and its double-shielding I suspect that the capacitance of the MSA-1 is far higher than the very low capacitance (12.2 pf/foot) of LC-1. If the sum of the capacitances of the cables to the two destinations is high and the unknown output impedance of the streamer is also relatively high the result would be rolloff and/or undesirable phase shifts in the upper treble, that would affect the signals received by the main speakers.

Also, if the resistance of the small shields of the MSA-1 is higher than the corresponding resistance of the larger shields in the LC-1 that could increase the chances that a ground loop issue might arise, depending on the unknown internal grounding configurations of the three components.

Based in part on my own experience with the Audioquest splitter as well as on my technical understanding of the situation I would have no qualms whatsoever about using them. And if that approach were to prove to be unsatisfactory (which I very much doubt in this case) I would feel certain that the cause is something else, such as an impedance incompatibility which your initial results already suggest is most likely not present.

Regards,
-- Al