This is what we found on Wikipedia regarding the Pain Of Truth:

House of Pain was an American hip hop trio that released three albums in the 1990s. The group consisted of DJ Lethal, Danny Boy, and Everlast. They are best known for their 1992 hit single "Jump Around", which reached number 3 in their native United States of America, number 6 in Ireland and number 8 in the United Kingdom. The group broke up in 1996.

Lead rapper Everlast went on to pursue a solo career as a blues rock artist and member of the supergroup La Coka Nostra which also featured DJ Lethal. DJ Lethal would later join and find commercial success with the rap rock band Limp Bizkit. House of Pain reunited briefly in 2010 for a world tour.

The group's name is a reference to the H.G. Wells novel The Island of Dr Moreau, a reference carried further by the naming of their 2011 tour He Who Breaks the Law; however, they initially became aware of the phrase via the Oingo Boingo song "No Spill Blood", of which they were fans.