I received this answer from Alan:
I saw your questions on the Axiom forums, which I monitor daily, as well as your PM, so here's what I suggest: the Axiom M80s do not have bass response to 20 Hz, so you shouldn't expect the woofers to reproduce loud output (or any output) at those frequencies. The M80 speaker has excellent deep bass to about 27 Hz, but no significant output at 20 Hz. You shouldn't feed test tones at 20 Hz to a speaker not designed to reproduce those tones, or damage may result. In fact, I'd suggest that if you are not familiar with lab testing procedures, don't use single test tones at all. You may use a pink noise signal, which I routinely use in speaker evaluation, as pink noise represents an equal amount of energy per octave across the audible spectrum. Single test tones may overstress any driver and cause damage.
If you want to reproduce energy at 20 Hz at high output, then a large powerful subwoofer is essential. I'd suggest Axiom's EP500 or a larger model.
By the way, there is almost no musical energy from any instrument, except very large pipe organs, below 30 Hz. Some movie soundtracks contain energy in the 20 Hz region or deeper, which is why large subwoofers are recommended for those signals, as well as pipe-organ reproduction.
The Axiom M80s are capable of very loud playback with no distortion of all music signals (not test tones!), ranging between 27 Hz and 20,000 Hz.
Some idiotphiles claims they burn new speackers by looping test tones.
I'm glad i never tryed it