Sigmar has been an active performer on the Icelandic music scene for several years, performing and/or recording with many of the most in-demand pop and jazz musicians in Iceland. In addition Matthiasson has performed at many international festivals, including Oslo Jazz Festival in Norway, Jazz Finland Festival in Helsinki, Bern Jazz Festival in Switzerland, Nordic Jazz Festival in Washington DC and Reykjavík Jazz Festival in Iceland.
His most recent solo project is ÁRÓRA that plays Matthiasson’s original compositions. In 2014 Áróra performed at the Reykjavik Jazz Festival in Iceland and the Young Nordic Jazz Comets showcase in Helsinki, Finland. In 2018 the group recorded it's debut album at Sigurros' legendary studio Sundlaugin. The album, entitled ÁRÓRA, will be released on September 7th 2018.