I am pretty sure what you are trying to do is also illegal. Those frequency bands are specially reserved for ADA hearing assistance. Proceed with caution.
47CFR §95.1009:
(a) Auditory assistance communications (including but not limited to applications such as assistive listening devices, audio description for the blind, and simultaneous language translation) for:
(1) Persons with disabilities. In the context of the LPRS, the term “disability” has the meaning given to it by section 3(2)(A) of the Americans with Disabilities Act of 1990
(42 U.S.C. 12102(2)(A)), i.e, persons with a physical or mental impairment that substantially limits one or more of the major life activities of such individuals;
(2) Persons who require language translation; or
(3) Persons who may otherwise benefit from auditory assistance communications in educational settings.
A creative interpretation of these rules might include that getting the audio signal to a remote set of speakers assists those with hearing difficulties. That said, I think there is legitimate justification if the event were an educational conference. (Obligatory disclaimer: I am not an attorney. Consult yours for more prudent guidance.)