"So you split the line level LFE and send the signal to a sub and to an amp for the buttkickers"

That’s one way to do it, or if your sub has pass through jacks you can connect that way also, or if your receiver has dual sub outs you can use one for your sub and one for the butt kickers. I have also used an inexpensive radio shack amplified AV distribution block to send the sub signal to multiple subs and butt kicker amps.

Go to this site
[Link: guitarvision.com]
Paste the following in to the search engine
Guitammer ButtKicker

Just an add on note about the cheaper A/V distribution amplifiers. The vast majority of them only buffer the Video. The If you open them up, you will generally find the audio is split simply by running a wire straight from the audio in and soldering it to each output jack.

If you need extra video outputs, that is fine. If you only need extra audio outputs, just use "Y" adaptors and save the money.

I am speaking only of the cheaper units. There are of course units out there that actually do buffer the audio as well.