The list of non-classical albums recorded in sacred spaces is small, but it’s led to some impressive sounds over the years. (Cowboy Junkies’ The Trinity Sessions is a particular favorite.) Grandbrothers, the duo of Erol Sarp and Lukas Vogel, recently created their own entry in that category with their new album Late Reflections. Recorded in the Cologne Cathedral, the album takes use of the space’s unique sound to create something vast and immersive. I spoke with the duo about the process that led to the making of the album and the challenges they faced along the way.