Prayer: Volume of the Imam's Voice
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1465
When reciting Sūrat al-Ḥamd and the other surah, and when saying the dhikrs that are said aloud, it is recommended that the imam of congregational prayers raise his voice to the extent that others can hear him; however, he must not raise it more than what is considered to be a normal voice.