Hooking up a REL Sub to a preamp that has 1 preout

Thanks guys for the response, that clears up my question. So if I had a tube amp that had 4&8 ohm connections, and I was using the 4 ohm, does the sub go on the 4 ohm as well or does it matter?

Check out the rel site..Its been awhile but I think you simply connect to the same taps as the speakers following color codes and one goes to ground..simple

You will hook it up to same taps as the speakers are hooked up to. Yellow to positive on left channel, red to the positive on right channel. Black to ground on either channel. Mine is on left but dont think it matters. If you need any help email me and I will try to help with any questions.

I use two and the advice you have been given is correct. Sumiko has a good set up guide on their site.