OK, just a few things- You do realize you have a sub rated at 750 WRMS, right? This means it is NOT intended to dissipate more thermal heat than 750 WRMS will generate. You have an amplifier that will probably generate well over 750 WRMS, this is more than enough power to fry the voicecoil... This has nothing to do with clipping, pre-out levels or anything else, contrary to what people may have told you. The voicecoil is a piece of wire wrapped around a former. It doesn't care what type of signal it gets as long as it's thermal threshold isn't exceeded. When you ask it to dissipate more than 750 Watts of energy, it overheats and breaks down. Period. This is always the end users fault. What is this crap about Xmax? The damn driver has 18mm of linear throw one way, that is more than many of the "SPL" subs out there, this has nothing to due with you thermally destroying the driver. It has an underhung motor. This more than likely means it has a shorter coil, with less surface area and lower heat dissipation. Again, compounding your user error even further. The geometry leads to an extremely flat BL curve within the excursion limitations, this means low distortion, low enough that you may not hear the driver being destroyed by your overpowering. This is a driver specifically targeted for flat, linear response. This comes at the expense of power handling in your case. My suggestion is to sell the drivers after you have them reconed (you should pay for this) and buy a sub that has higher power handling due to the fact that you cannot tell when you exceed your drivers thermal limits. To be safe, you should buy a driver that has 2X the RMS rating as your amp.... This is not a general reccomendation, this is only for you.