Is it obligatory for people of knowledge to stand behind the Imam and convey his voice in prayer, despite the presence of loudspeakers, based on the hadith: "Let those of you who are mature and discerning stand directly behind me," and to avoid the general public and the ignorant standing behind him?

We advise you to be diligent in occupying the first row and to counsel the Imam regarding the reprehensibility of verbal amplification (tabligh) when there is no need for it, and that scholars are in agreement on its reprehensibility, though they differed on whether it invalidates the prayer. Sheikh al-Islam Ibn Taymiyyah stipulated that it is not legislated to vocalize the takbir loudly behind the Imam unless there is a need for it. He cited the Hadith (definition) of Abu Bakr when the Prophet, peace and blessings be upon him, was ill, and mentioned that tabligh is legislated when there is a need, such as a weak voice from the Imam, otherwise it is reprehensible by the agreement of the madhhabs. Sheikh Ibn Baz mentioned that tabligh is not legislated except when there is a need, such as the vastness of the mosque or the weakness of the Imam's voice. If someone else undertakes the tabligh, there is no harm, and your standing in the first row does not necessitate you performing tabligh. If the Imam stipulates tabligh as a condition for entering the first row, and you fear falling into scholarly disagreement, then leaving the first row is easier, or praying in another mosque is preferable.