D.C. Mun. Regs. tit. 24 § 208
No entertainment or music shall be provided or permitted for the enjoyment of the patrons of the establishment operated on public space by a permittee other than music as may be furnished by no more than three (3) musicians playing stringed instruments such as the violin, the viola, the cello, the double-base, and the guitar, and no more than one (1) accordion or concertina.
Music allowed under § 208.1 shall not disturb the peace or quiet of the neighborhood, or the comfort or repose of any inhabitant of the neighborhood. This music shall not exceed sixty (60) dB(A) or the applicable decibel level for the zone from which the music emanates when measured at the property line of the establishment from which the music originates.
No music shall be played before or after the hours within which the music may be played as specified on the face of the permit issued for the use of the space, or later than 12:00 midnight.
There shall be no amplification or production of music by any electronic or mechanical means, including any electronic or mechanical reproduction of music and its dissemination by means of loudspeakers, whether by coin-operated or non-coin operated phonographs or music boxes, by background music service, or by any radio or television set.
D.C. Mun. Regs. Tit. 24, § 208