see audio tipitaka page for more detailed info of this sutta https://sites.google.com/site/audiotipitaka/home/khn/khn-khp/khp-9 (includes recited versions, chanted versions, multilingual)
Thanissaro and Wat Metta Sangha mp3 file came from http://www.dhammatalks.org/ direct file link: http://www.dhammatalks.org/Archive/Chants/15%20%20Karaniya%20Metta%20Sutta%20%28p%2095%29.mp3
Bhante Gunaratana's mp3 file I could not find on a fixed web location that hosted it. I found it on a bit torrent. I believe it is extracted from one of the dhamma talks at bhavanasociety.org . The volume was low so I boosted it (audacity "normalize" function).
Dhammaruwan's chant comes from http://www.dharmaseed.org/teacher/52/ The volume was too low so I boosted it (audacity "normalize" function).
More info about these following two files on this page: https://sites.google.com/site/audiotipitaka/home/khn/khn-khp/khp-9 metta_skpfrank_k_normalized.mp3 metta_skpfrank_k_normalized_noise_cleaned.mp3