Speakers are typically 5 to 10 percent efficient. You can never get 100 percent of the electrical energy into sound because the driver cone to air impedance coupling is so mismatched that it cannot be a perfect "transformer". But the other factors involved - the mass of the driver, magnetic energy, ports, box construction, etc. - all vary from speaker to speaker. For example, if a speaker is 90 dB at one watt at one meter, and it is 10% efficent, if all the power went to the speaker it would be as if the power was multiplied by 10. A power multiplier of 10 results in 10 dB or 100 dB/W/m. But other speakers have differing sensitivities due to different drivers, crossovers and construction, so there are tons of theoretical answers.
It's similar to asking: how fast can a car (about 20% efficient) go if all the energy in gasoline is converted to velocity. You would have to establish a base weight and ignore heat, braking, steering, electrical devices, lights, friction and other physical quantities. Cars have different weights, so the answer depends on a given weight, of which there can be an infinite possibility.