subwoofer pre outs mono or stereo signal?

I have a Pioneer Premier DEH-P500UB CD player and recently purchased an Hifonics ZXi150.4 amplifier to run speakers in my vehicle.  To run this 4-channel amplifier in a 3-channel configuration with a set of 6.5 components and a single 2ohm DVC subwoofer, it says that channels 3/4 of the amplifier require a mono signal for the subwoofer.  I would like to use the subwoofer RCA preouts on this Pioneer head unit to supply the signal to my amp so that i can use the related subwoofer functions on this head unit. 

My question is, are the two (red and white pair) subwoofer RCA preouts on my head unit a stereo signal or are each one the same mono signal?  If they are a stereo signal, can I use the white subwoofer preout only and connect a y-splitter cable to make a mono signal for the amplifier from the head unit?  Any help would be appreciated.  Hopefully this isn't one of those questions that is been beat to death already.  I tried searching on here, google, and yahoo, but can't find an answer.

Thanks,

Eric

Wow, it does say that.  I downloaded that manual and read through it probably three times and missed that each time!  I even sent Pioneer customer support an e-mail asking them about it (Their answer was for me to call them...   so helpful).  I really appreciate the time that you took to look that up for me.

Now I have to figure out how to read the graphs on WinISD to make a vented box for my subwoofer.  The best design I can get, with a box size that will fit and low enough rear port air velocity, has a shape closer to a bell, with a peak of about 3 1/2 db at 36hz, than a straight line.  You wouldn't happen to be able to describe for me what a proper looking graph would be like, would you?

Thanks again for the help with the Pioneer head unit.

Eric