I thought that aswell, god knows want amp he's really getting.
Anyway, you said the D40 will start to sound muddyat 30Hz, Is this frequency often used in music ?. I oticed my Z5500's go to about 33hz, so would start to sound rubbish at about 45hz, I have only ever heard to sub struggle with low frequncies 3 or 4 times sinse ive herd them, i could tell because it sounded muddy and distorted at a low volume, and it was very low. So i figured this was why.
So, although the D40's will sound worse when it gets to very low frequencies, is this likely to happen often ?
Im still going to read reviews on both, see what other people say.
I'd go with crysalis's advice. not everybody has a ear for music. he's an audiophile and engineer. most people think that an 80 hz note boosted by 12 db (which will distort it) is a 20 hz note.
you best bet is to audition them and make your own conclusion. you are likely to find out that crysalis is right