Set-up with two subs and an integrated amp

Call crutchfield for the subwoofer subwoofers adapter.
it has several small resistors under $30 ,you can buy 2 pair of
screw or crimp on bananas or spades you need to hookup
tp the loudspeaker terminals..

Millercarbon,

That is wonderful information. Thanks. Why is no one listening? Oh, I know, they're too busy listening to  themselves.

I've noticed by some of your comments that we may have more in common than one would think. Besides a shared appreciation of the RSL 3600s I should tell you that I also go by SpdYlw993.

Porsche Panorama Technical Editor Alan Caldwell had the most perfect 914 you ever saw. Speed Yellow over black. Al also had a Speed Yellow over Black SC. When he showed up at a concours with a brand new 996 I looked it over real good, walked up to Al and said, "Speed Yellow and Black?" Without missing a beat he said, "Is there anything else?"
When one day my wipers stopped returning to park I went looking for answers. None of the (seriously good) Porsche techs new for sure what it was. Unwilling to start throwing money at the problem but running out of ideas I turned to Al. "There’s a little copper tab inside the switch. It loses its spring after a while. With a toothpick you can bend it back." Sure enough. Saved me a thousand dollars. At least.

Pays to listen. It really does. Some of us figure it out.

Instead of using resistors, could a step down transformer be used on the amplified output?
For an example Jensen might have one off the shelf that could work?
I would certainly check the voltage with a multimeter after dropping the voltage for use with the sub.

Also, the sub itself has a volume control?

Your first response from "mattmiller" is a good one. First off I have several REL subs and they all have no peer in their price / performance category. Actually a pair of the entry level subs will do an amazing job when carefully set up. "Speaker level" connections are always the best way to go. Virtually all audio critics will agree to that. The REL's come with a cable that has a "speakon" connector to plug into the sub. The amplifier end can be connected parallel with the sattelite speakers. One sub parallel with each channel. The REL manual will provide info on the correct connectivity. There are also after market cables designed and terminated with quality connectors, that would be a slight upgrade from the ones supplied by REL. Also the supplied cables are quite long to accommodate almost any possible setup. Once you have determined the ideal locations for the subs, you should be able to buy the aftermarket version cut to a more appropriate length, unless you prefer to do it yourself. That's my recommendation !
"SPEAKER LEVEL CONNECTIONS" 

Congrats on interpreting the OP's query millercarbon. Good answer.