What might be causing this problem? Is my speaker wire crossed?

[CanadianCoupe]

I connected a set of component speakers and 6x9's to a 4-channel amp. I am getting great sound to the comonents, but with the 6x9's I can hear the vocals very quietly and there is a constant clipping sound.

What causes this problem? Is my speaker wire crossed or is my signal cable crossed?

[AppleBonker]

The fronts sound ok? Did you try swapping the wiring to run the rears off the amp where the fronts are running now? That would rule out the amp.

Then, run the rear RCA cables into the front inputs to make sure the fronts still sound ok (this will rule out the RCAs).

If both of those don't shed any light, it looks like there might be a speaker wiring issue just to the rears. Try replacing the speaker cable to the rears and see if that works. Let us know what you find.