The genre entered a golden age in the 1970s as singers known as qawwals battled for prestige, with the Sabri Brothers - led by Amjad's father, Ghulam Farid Sabri - and Nusrat Fateh Ali Khan finding audiences around the world. Performances traditionally last hours, with a troupe of musicians interweaving soulful improvisational threads under lyrical, lilting vocal lines to a steady beat of thundering rhythms on dholak and tabla drums and hand clapping, sending fans drifting into trance-like transcendent states. "Why do they hate qawwali? Why do they hate music?" Embraced widely as a part of Pakistan's national identity, qawwali has played a key unifying role, with city-dwellers and villagers flocking to Sufi shrines for concerts.
"I am still in shock," Sabri's brother Talha told AFP from his family home adorned with pictures of his superstar sibling, whose fame spanned the subcontinent and beyond.
His murder was just the latest in a series of blows in recent years to strike at the heart of qawwali, which has thrived in South Asia since the 13th century. "He was a rockstar of the masses," explained journalist and musician Ali Raj, who studied under Sabri.
Thousands poured into the streets near Sabri's family home after his death for his funeral, a rare public display of affection in Karachi.
Nearly two years after Pakistan's foremost qawwali singer Amjad Sabri was gunned down in Karachi, the devotional music of Islam's Sufi mystical sect is struggling to survive, as fears of sectarianism and modern pressures slowly drown out its powerfully hypnotic strains.