Hi!

That gives me an idea for testing subwoofers ...

Connect each speaker terminal to the active and neutral of a
mains supply.

Now come on, haven't you watched enough Youtube to know what happens
when you do that? ;-)

Interestingly, the very idea of connecting a speaker to the AC line is
mentioned early on in my copy of the ARRL's "Now You're Talking" book.
They tell you not to do so, and I suppose that there are some people
out there who need to be told that...more so because they'd hurt or
kill themselves in the process.

William