sub in the fireplace

Two suggestions:
1. Make sure if you use acoustic foam that it is not flamable.
2. Never let Ben Stiller in your home to "Meet the Parents", he might just set a blaze to the sub/s. Sorry just saw that movie and it seems like sometihng he would do.

If they use a downward firing sub, be sure not to install it upside down. This would scare Santa and if he lands on the spikes it will surely be a bag of coal for your parents.

It's not a fireplace; it's a custom sub enclosure.

That chimney would make a helluva transmission line, wouldn't it?

Expensive Duraflame log? I think they're going to have to experiment with that one and then post the results. Elgordo - whats the best listening position for that transmission line? Would it be in the basement or on the roof? Streetman, good luck to your parents.