Nominal Impedance of subwoofers?

[Kursun]

You mean your Rotel is heavier than the whole subwoofer, or can you separately weigh the amp unit on your 400 W sub?
Anyway, your sub's amp may have a switching mode power supply which is a whole lot more efficient and lighter than conventional power supplies (just like the ones in PCs and car audio amplifiers). But they may have rf interference problems.

[kexodusc]

Just some quick math, MDF and particle board weigh so much, etc...I didn't take into account the cabinet of the Rotel.
I realize it's probably not an adequate comparison, I was just a little curious. Thanks for your help.