I notice that my speakers distort and seem very unefficient when I use all 4 on front (a+b) at somewhat loud volumes, while when using only one pair on front they sound better and are more efficient and I've never heard them distort. One speaker blew and I think it's because I was pushing them using four fronts at the time. Is using four fronts at louder volumes taxing the reciever to where it distorts and then is blowing, distorting, and damaging my speakers? Thanks