99.99999% of the people who are going to give you and answer have no idea what the impedance they are presenting thier amplifiers actually is. So honestly, you aren't going to get any objective answers to this unless someone has a swept impedance curve of thier subwoofer system and the amplifer you are talking about. This is kind of the problem and where so many different opinions come from, they are not based on any sort of facts, just gut feeling. You can get in trouble because guy X runs the same subs as you and the same amp and is fine, but your box may have a completely different impednace curve and you might cook your amp where guy X was fine the whole time...