The Bothy Band's 1975 debut redefined ensemble playing with sheer momentum. Matt Molloy's flute, Paddy Keenan's pipes and Tommy Peoples's fiddle play in fierce unison, while Dónal Lunny's bouzouki, Tríona Ní Dhomhnaill's clavinet and Mícheál Ó Domhnaill's guitar build a rhythm section with real…