I was running subwoofers in stereo off of my amp not too long ago. *The
only time it could cause problems is if you have both your subwoofers in
a shared chamber AND they encounter stereo bass. *Stereo sub bass
frequencies are rare in this day and age.
OTOH, if you listen to One of These Days by Pink Floyd, you may notice
the stereo bass 
The subs are in a shared box. And I do occasionally listen to that
type of music.
Then again, I automatically assumed Dreadnauts when you said MMATS.
Old Mmats Wavedrive(?). SVC
PS *If you decide to get your amp fixed, I suggest looking into dB-r
electronics: *http://www.db-r.com/
Thanks for the link on this guy!
So i did wire the 4080 up. Following the amp's manual. That thing is
loud! Way loud! Maybe too loud? I have the gain turned almost all
the way down. This is how I wired it.
The Rear output Left+ goes to the speaker Left-
The Rear output Right- goes to the speaker Right+
The Front output Left+ goes to the speaker Left+
The front output Right- goes to the speaker Right-
2 channel input BTW, not 4.
Is this series or parallel? What kind of impedence are we looking at?
There's no way in heck this Rockford can out-perform the old PPI
A600. What's the deal? I don't want to blow this up by doing
something stupid.