Depends on what the in-box impedence is. It is likely that the amp would hardly ever see an impedence lower than 2ohm (for an extended period of time) even though the subs are wired to 1.5ohm. So it could very well be just fine.
Only one way to find out though.....try it out //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif If you let the smoke out of the amp, then you know it didn't work //content.invisioncic.com/y282845/emoticons/satan.gif.9c6a335ed7aeeed3ee273e573f1fcaac.gif