Using a microphone for Salaah

If the Imam recites Qirat by mouth and there is only 3 lines (saffs) of musallees and the sound by mouth reaches till the 20th line (saff), but still he recites qirat using the microphone and the sound of the loud speaker reaches 5 decibles which can be heard in the building beyond the mosque. The sound level for the 1st line (saff) of musallees is about 95 decibles (dB).

1. Though the mouth is enough, still using the mike and loud speaker, is it tasarruf?

2. When the sound level (dB) goes up beyond the permissible limit (60 dB) what should we do?

3. During the Fajr prayer when the qirat is going on so loudly, it is very difficult to pray sunnat of Fajr.

4. Though the mouth is enough, still using the loud speaker, is it riya?