If the installation of this equipment does nothing more than improve the sound inside the mosque, there is nothing wrong with it, but if it makes the sound of the letters reverberate then it is haraam, because it means that it is adding a letter or two to the recitation, and changing the words of Allaah to something other than that which was revealed. It says in al-Iqnaa’: Ahmad regarded it as makrooh to recite in a wavering choice and he said: it is an innovation. If it also results in changing the pronunciation of the Qur’aan and making the vowels sound like letters, then it is haraam. End quote.
But if the sound comes out of the mosque from the top of the minaret and there are no other mosques around whose worshippers may be disturbed, or dwellings whose people will be disturbed by the sound, then I hope that there is nothing wrong with that. But if there are other mosques around whose worshippers will be disturbed or dwellings whose people will be disturbed by the sound, then it should not be done from the top of the minaret, because that is annoying and disturbing others. It was narrated that Abu Sa’eed a-Khudri (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) observed i'tikaaf in the mosque and he heard them reciting Qur’aan out loud. He drew aside the curtain and said: “Each one of you is conversing privately with his Lord, so do not disturb one another and do not raise your voices above one another in reading Qur’aan, or in prayer.” Narrated by Abu Dawood. A similar report was narrated by al-Bayaadi Farwah ibn ‘Amr, as was narrated by Maalik in al-Muwatta’. Ibn ‘Abd al-Barr said: The hadeeths of al-Bayaadi and Abu Sa’eed are saheeh. Shaykh al-Islam Ibn Taymiyah said: No one should recite Qur’aan so loudly that he annoys others such as those who are praying. End quote.
Majmoo’ Fataawa Ibn ‘Uthaymeen, 15/160.