All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
The worshipper should not preoccupy himself by listening to another person's recitation of the Quran while engaged in prayer, whether he is praying individually or is the Imaam in congregation. This is because the worshipper is enjoined to engage in his prayer and observe Khushoo‘ (submission). Muslim scholars stated that it is disliked to listen to the recitation of the Quran of another worshipper while engaged in prayer. Al-Khateeb Ash-Shirbeeni wrote, "It is disliked for the worshipper praying individually and the Imaam in congregational prayer to listen to the recitation of the Quran of someone else during the prayer." [Mughni Al-Muhtaaj]
The Shaafi‘i book Al-Minhaaj Al-Qaweem reads, "It is disliked for the worshipper to listen to another person's recitation of the Quran during the prayer except his Imaam."
What you mentioned about this helping you concentrate cannot be true. Concentration (or Khushoo‘) denotes the attentiveness of the heart during the prayer, which enables the worshipper to attentively reflect on what he does and says during the prayer without allowing anything outside the prayer to distract his heart. The Hanafi scholar Ibn ‘Aabideen wrote, "You should know that the attentiveness of the heart in the prayer means removing all extraneous thoughts from one's mind and heart, keeping them free of whatever may distract them. In this context, it means being fully aware and attentive to whatever the worshipper does and says while praying." [Haashiyat Ibn ‘Aabideen ‘ala Ad-Durr Al-Mukhtaar]
Scholars considered that preoccupying oneself with anything extraneous to prayer is disliked, even if consists of inner thoughts about the Hereafter. The Haashiyah of Al-Jamal defines Khushoo‘ as follows: "It is the attentiveness of the heart by not being distracted by extraneous thought while in prayer, even if these thoughts are about the Hereafter. If the worshipper preoccupies himself with thoughts about Paradise or Hellfire or any other religious matter that is extraneous to prayer, it is disliked."
So, we advise you to strive to attain Khushoo‘ in prayer and not preoccupy yourself with anything outside prayer even if it is listening to the recitation of the Quran.
For more benefit, please refer to Fataawa 85048 and 117350.
Allaah Knows best.