Ruling on the imam walking in the direction of the qiblah to reach the microphone so that the people can hear him
Question

                During Taraweeh prayers, the electricity cut out. Because of that, we started to pray in the rear part of the mosque, and that was because of severe heat. During the prayer, the electricity started working again, and suddenly the imam began to walk, whilst reciting, across a large distance, approximately 25 meters, in the direction of the qiblah, in order to reach the microphone, but as members of the congregation we did not follow him in that. After the prayer, we asked him: What made you do that? And he said that he moved in order to reach the microphone, because after the electricity came back and the fans began to work again, perhaps the women on the upper level might not be able to hear his voice properly. Please advise us about the issue of his moving across this distance and how permissible it is. What are the limits on moving whilst praying? Does it make a difference whether the prayer is obligatory or voluntary? How much may a person move (during the prayer) in the case of necessity?
Praise be to Allah.Firstly: 
It is permissible to move whilst praying if that is in the interests of the prayer, even if that entails a great deal of movement. al-Bukhaari (403) and Muslim (526) narrated that ‘Abdullah ibn ‘Umar said: Whilst the people were praying Fajr in Quba’, someone came to them and said: Revelation came to the Messenger of Allah (blessings and peace of Allah be upon him) last night and he was commanded to face towards the Ka‘bah, so face towards it. They were facing towards Syria, so they turned to face the Ka‘bah 
Ibn ‘Uthaymeen (may Allah have mercy on him) said: This indicates that it is permissible to move (whilst praying) if that is in the interests of the prayer. 
End quote from Majmoo‘ Fataawa wa Rasaa’il Ibn ‘Uthaymeen (12/354) 
Moving during the prayer is divided into five categories, according to the reason for it. If the reason for it is something obligatory, then moving is obligatory. If the reason for it is something prohibited, then moving is prohibited, and so on. For more information concerning that, please see the answer to question no. 12683. 
Based on that, with regard to the imam’s moving forward in the direction of the qiblah in order to reach the microphone so that the women could hear his recitation and takbeer, if his voice was not reaching the women or there was excessive difficulty in enabling the women to hear the recitation of the imam, then his action was correct and Islamically prescribed, because it was in the interests of the prayer. 
Abu Dawood (922) narrated that ‘Aa’ishah said: The Messenger of Allah (blessings and peace of Allah be upon him) was praying with the door closed, then I came and asked for it to be opened, so he walked and opened it for me, then he went back to the place where he was praying. And he mentioned that the door was in the direction of the qiblah.
Classed as hasan by al-Albaani in Saheeh Abi Dawood. 
Ibn Khuzaymah (827) narrated from Ibn ‘Abbaas that the Prophet (blessings and peace of Allah be upon him) was praying when a sheep passed in front of him and he raced with it by moving towards the qiblah (to prevent it walking in front of him), until he pressed his stomach against the wall (which was in the direction of the qiblah).
Classed as saheeh by al-Albaani in Sifat as-Salaah (p. 83) 
Ibn ‘Abbaas (may Allah be pleased with him) prayed with the Prophet (blessings and peace of Allah be upon him) and stood on his left, and the Prophet (blessings and peace of Allah be upon him) moved him and made him stand on his right.
Narrated by al-Bukhaari (138) and Muslim (763). 
If the women could hear his voice without amplification, but they would hear it more clearly and better with amplification, then what he did was not proper and in fact was extremely makrooh (disliked), because he did a lot of movement that he did not need to do, which might have resulted in distraction of the worshippers during the prayer, and caused confusion during the prayer and led to them disputing after the prayer. 
Secondly: 
With regard to the limits on moving during the prayer, the guideline is that it is permissible if it is in the interests of the prayer, even if it is a great deal of movement. But if it is not in the interests of the prayer and there is no need for that, then it is makrooh even if it is a little movement, and the prayer is rendered invalid by it if there is a great deal of movement. 
Al-Mirdaawi said in al-Insaaf (2/129): 
Actions which are usually regarded as being a great deal and that are not part of the prayer render it invalid whether that is done deliberately or otherwise. It should be noted that the prayer is rendered invalid by a great deal of movement that is done deliberately, and there is no difference of scholarly opinion that I know of concerning that. It is also invalidated by that (great deal of movement) if it is done absentmindedly, according to the correct view, and it was narrated by the commentator and others that there was consensus on this point. 
What is meant by the prayer being rendered invalid by a great deal of movement is if there is no need for that. End quote. 
Thirdly: 
The Sunnah is for the believer to focus on his prayer with proper humility, both mentally and physically, whether it is an obligatory or supererogatory prayer, because Allah, may He be glorified, says (interpretation of the meaning):
“Successful indeed are the believers
Those who offer their Salat (prayers) with all solemnity and full submissiveness”
[al-Mu’minoon 23:1-2]. 
There is no difference in the rulings between obligatory and supererogatory prayers except in matters for which there is specific evidence. Ibn Qudaamah (may Allah have mercy on him) said: 
Whatever invalidates an obligatory prayer also invalidates a voluntary prayer.
End quote from al-Mughni (2/47). 
But there may be more causes for movement during a supererogatory prayer than in an obligatory prayer, because supererogatory prayers are usually done at home, which makes it more likely that some urgent matter may arise which requires the worshipper to move, in contrast to the obligatory prayers which are usually done in the mosque,as we have seen above in the hadith about the Prophet (blessings and peace of Allah be upon him) opening the door for ‘Aa’ishah. Ibn Hazm also narrated in al-Muhalla (2/126) from Mu‘aadhah al-‘Adawiyyah that ‘Aa’ishah the Mother of the Believers used to instruct her servant to share out the broth, and she would pass in front of her whilst she was praying, and she would gesture her to add more; and she would instruct that something be given to a poor person, gesturing to that effect whilst she was praying. 
It was also narrated from Mu‘aadhah from ‘Aa’ishah the Mother of the Believers that she stood up to pray wearing a chemise and headcover, and she pointed to the wrapper and I handed it to her; there were other women with her and she gestured to them with her hand to have some food – i.e., whilst she was praying. 
Fourthly:
The extent to which it is permissible to move whilst praying is known by the extent of the need to do so. If the need is something essential, such as moving in the interests of the prayer, or moving to kill a snake or a scorpion whilst praying, or moving to save someone from drowning or dying, then there is no blame on the worshipper for that, and in fact he may be instructed to do it.
But if the need to move whilst praying is not essential, then the ruling on the movement is connected to that, and it varies according to the reason for it, as you will see by referring to question no. 12683 
Based on that, what appears to us to be the case is that there is no blame on the imam for what he did in his prayer, if there was a problem in his voice reaching the women. What the people praying behind him should have done was to follow him in his prayer, especially since it was not clear to them for certain whether he was mistaken in doing that. 
And Allah knows best.