Second sub connection


A basic question but then again basic is the limit of my audio knowledge. I currently have a Schiit Freya preamp with two rca outputs. One output is running a pair of tube amps the other was for an older Quad subwoofer with rca L and R inputs. I just purchased a second sub (svs pb2000) with the same inputs. I had a brief conversation with SVS and was told to run a pair of cables to each sub with splitters.
i have an old pair Radio Shack Y splitters male to female and could put one in each channel of the second output and run a pair of cables so each sub is getting a right and left feed.First...is that correct or should I run one sub only left and one only right?
Second...could I use different splitters on the sub end (dual male to one female) and run one cable each from the the preamp L and R to the subs.
The second application would save me some money on cables. I already have a pair of 12 foot cables that were to my first sub, the second sub would need a 22 foot run. So I thought if I took one of the 12 foot cables and patched it to a 10 foot cable I could run that to new second location if I were to split at the sub end. Not knowing the difference because of my current cables one is coded red for right and the other black for left (normal) so is that going to present an issue separating them. Don’t want to compromise on the connection to save money but I would like to understand better how this works.
Thanks for any responses that might shed some light 💡.
Dan

danham
Do not have intimate knowledge of your subs, but usually there is a mono option, usually the left channel being mono.  

If so, simply connect the left channel output of the preamp to the mono of the left sub, connect the right channel output of the preamp to the mono of the right input.

That's my best shot.  If anything catches fire, I recuse myself and accept no responsibility. 
Thanks for the responses. I have an LFE on the new SVS but not on my older Quad. So would putting the y splitters on the sub end and running a single cable to each sub accomplish the same thing. I don’t need to feed a left and right channel to each sub?
I just run a single cable to each of my two subs from a pair of y splitters at the preamp end.
Sounds fine to me
Uberwaltz...sorry not to pick up on this right off but the y splitters I have would leave 4 open ends plugging one in each channel off the pre, how do we get a single cable going to each sub. Would running a single cable out of each of the preamp channels into a y splitter feeding L and R on the sub end create a problem?