There's not much comfort in the copyright law (below), it's not a first sale issue but rather one of public performance. But there is comfort in the fact that the market hates a margin. And the last time I checked, horizontal price fixing is still a Sherman Act violation.
§ 106. Exclusive rights in copyrighted works38
Subject to sections 107 through 122, the owner of copyright under this title has the exclusive rights to do and to authorize any of the following: .....
(4) in the case of literary, musical, dramatic, and choreographic works, pantomimes, and motion pictures and other audiovisual works, to perform the copyrighted work publicly;
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