Connecting amps to preamp

I have a Carver C-1 preamp with Main 1 and 2 out, which says either under the RCA ports. Can I connect the TFM-55x to 1 and the C-760x to 2 to drive front and rear Magnepan speakers? I also have an Infinty powered Sub with only 1 set of rca inputs and the C-1 does not have a Sub output. How can I connect this?
I don't believe you will be able to control the volume individually making this not a good idea. You want the rears at a lower level than the fronts in a surround set-up. Which gives you the out put you need for the sub. You could also run an output to the sub and high pass it to a pair of speakers (depending on what kind of sub)
I have Gain controls on the rear amp. The sub doen't have any outputs. should I use a rca Y cable?
Yes- a Y cable will work