Dogma4e wrote:

And you call that a competent test of the flammability of your
speakers? For Christ's sake, why don't you pony up and bring a set
over to Underwriter's Lab? I think they're in your neck of the woods.
Take a schematic. They will overdrive them for several hours, measure
delta T, and if they don't blow up you will have a UL listing.
Probably cost you about $2,400, and they'll let you pay ove time.
They'll want to inspect your cough, cough... factory, but they've seen
worse.

Good point, actually. We all missed this. If I was selling speakers,
I'd get them tested. The bookshelves, not really required. The sub?
Absolutely. It has an amplifier, afterall, and 120VAC running to it.