Is it permissible for a Muslim engineer to install DJ equipment in hotel ballrooms if the employer is Muslim?

It is not permissible to install equipment in dance halls because it is cooperation in sin, and Allah Almighty has prohibited cooperation in sin and aggression. Whoever assists in disobedience will be held accountable, just as ten people were cursed concerning wine, and in usury, its consumer, its provider, its scribe, and its two witnesses were cursed. Thus, every assistance in what is unlawful is forbidden.