RCA Outputs, can you convert?

[trpower7]

So I want to wire up a 4-channell amp. But my head unit only has one set of pre-amp outputs. Can I just take the speaker level ones and wire them up to RCA terminals (you can buy them at RadioShack) and then plug them into the RCA inputs? Or will I be forced to try to find one with speaker level inputs. Or just use two channels on all of my speakers? I really dont' want to buy a new head unit..........

[1dollar240]

radio shack makes a little box that converts speaker level outputs to rca. The quality wont be as good but it will work.

[not_a_porsche]

You can also split the preamp out from the head unit. That should have no loss in quality.