Is it permissible to perform supererogatory and daytime Sunnah prayers aloud at home or in an empty mosque?

Voluntary prayers at home are better than those in the mosque, according to the Prophet, peace and blessings be upon him: "So عليكم بالصلاة في بيوتكم، فإن خير صلاة المرء في بيته إلا المكتوبة" (You should pray in your homes, for the best prayer of a person is in his home, except for the obligatory prayers). The Sunnah for voluntary daytime prayers is to perform them silently, not audibly, except for what has been specifically exempted.