Bridging amp / speaker wire problem.

I have two NAD amps, c270 and the c370, both with identical power capabilities. I and
running both of them in mono to a set of B&W 602 speakers. Sounds fantastic. One
problem, I have a set of Audioquest Type 4 speaker cables with four connections at the
speaker ends and two at the amp end. A very strange thing is happening, I get only highs
out of one speaker and only lows out of the other speaker? What is the problem? When I
connect the speaker jumpers on the negative side, it clears up the problem. Can any one
offer help?
make sure the negatives (black) of the speaker cables are going to the negative (black) terminal of the speakers and the positive (red)tothr positive terminal on your speakers

and the negative black of the speaker cable is going to the negative terminals of the amps and the positve (red) of the speaker cable is going to the positive (red)terminal of the amps...

sounds like you have something switched

I tried all of your suggestions and then some! I cannot figure out what is going on! Would it have anything to do with how I have my two amps connected together? I have an innerconnection cable running from my integrated amp's (L)pre-out 1 to the fixed (L) input of my amp. My integrated amp has two out puts, pre out 1 and pre out 2, which is variable. It also has MAIN-INS. The instruction manuel says to connect the interated amp through the MAIN-INs, but, this does not work.