He learned from Donegal fiddle masters including Con Cassidy, James Byrne, Francie Mooney, Dinny McLaughlin, Vincent Campbell, and Francie Dearg Ó Beirne.

Dermot usually performs solo and unaccompanied, which is unusual in Irish traditional music these days.

He also teaches at summer schools, masterclasses and other events and prefers to work with small groups or individuals.