In the past I've done some non-scientific testing of my own with my old school Radio Shack dB meter and I'm able to easily obtain a 120dB A-weighted reading by feeding pink noise from a single Acme Low B2 4-ohm unit from a 500-watt per side PA amp without the light bulb 'fuse' lighting up or the speakers becoming distressed or excursion being anywhere near their limits. This was at a 10 foot listening distance (ie. the typical distance from a cab when at a gig on a small to medium size stage). I should have got that on video, would make for a good YouTube.
I don't know how this relates to the 1W/1M sensitivity ratings, but my Acme Low B speakers have no issue being deafeningly loud even with a modest amount of power.
By the way, I've only blown the bulb once in one of my cabinets and that was while I was playing with some high gain distortion out of my Zoom pedal and I turned and faced the speaker. My bass's pickup and the Acme's tweeter were about 6 inches from each other and I heard a loud squeal of feedback, saw a bright flash, and then all the highs and mids were gone. The bulb was blown but it did its job of saving the tweeter and midrange woofer.
And in addition to all the above, I have an 8-ohm Acme Low B2W, the 'subwoofer' edition that is exactly the same except it is missing the crossover, tweeter and midrange. The wiring jack wires directly to the bass woofers without any sort of crossover or filtering and is run full range. I've occasionally used it as a subwoofer with my Mackie SRM 450 mains and it works fantastic, but you can pretty much do the exact same thing with the Acme Low B2 and just turn down the mid and high attenuator knobs to achieve the same effect.
