alot of people say that but i have to dissagree, the power handling will increase in the frequency range it likes and then will loose powerhandling in the areas it doesn't
but at the same time as long as the box is properly designed you will have no problems
i test every sub box i build on my 7232, and believe me, the subs i've hooked up to it take it with no problems,
type R's, mtx 8000's $100-$200 range subs
i had a mtx 8000 10" in a box i just made for my friends car straight hittin
it was in 4 ohm, but were talkin about a shit ton of power