[mdmathis6]

Yeah and because they are made of stronger yet much more lighter/transient enhancing materials, they are more efficient than they used to be.

[eddie willers]

General information for all following this thread:
(and thanks, mdmathis6, for telling my brain why my ears like what they hear)

One of the primary benefits of the new Dolby Digital receivers (and preamps) is that they have an electronic crossover built-in with the assumption that you will be using a powered sub-woofer.

Most are fixed at 80 Hz, although some of the newer designs will give you several cut off points to better match the size of your front speakers in a 5.1 surround sound set-up.

This allows the receiver's amplifiers more headroom since they are not trying to reproduce any frequencies below 80 Hz and the speakers to play clearer since the (typical) 5.25" / 6.5" drivers are not being asked to play that which they cannot. (low bass)

Since today's sub-woofers are self-powered, all they need is a low level signal from the receiver to tell it when to go boom.