He has participated in international courses with teachers like David Russell, Hopkinson Smith, Manuel Barrueco and José Tomás Pérez Sellés.

Later Halldor Mar crossed Iceland and Spain, both as a soloist and as a member of "Mosaic Barcelona's Guitar Quartet".

He worked with guitarist and composer Eduard Rodes to perform a piece called "The Light", inspired by the life of Francesc Ferrer i Guàrdia, who was a free-thinker executed in 1909, following the Tragic Week riots in Barcelona.

Halldor Mar returned to work on Eduard Rodes 2006 album República Mediterránea, interpreting the theme in "In Iskandariyah".

With the passage of time he began to create his own music, presenting concerts in small Irish pubs, years after participating in Barcelona nightlife.

It received good reviews from music media such as the magazines MundoSonoro,[1] Binaural,[2] and Planeta Indie.