Dahl came from a literary family; his father was translator and provost Jákup Dahl. His own poetry has been described as more modernistic than many previous Faroese poets. His family also contained musicians like his grandfather Georg Casper Hansen; Dahl is also noted as a composer. In youth he did not know how to transcribe his compositions so would work on them in his head before performing them at cultural events. As a composer he wrote musical settings for 34 Erik Axel Karlfeldt poems and made around 450 compositions in all.
Dahl was honoured in 1998 with the Faroese Cultural Prize. He was the first person to receive this award. It has been given to a Faroese artist (writer, musician, painter etc.) almost every year since 1998.