He Also Did: live keyboardist/backing vocalist Einar Solberg is the frontman of Leprous, another band from Emperor's hometown of Notodden, Norway. The band have reached huge critical acclaim amongst the progressive metal community (they've also performed as Ihsahn's backing band live). Solberg also appeared on some albums by Emperor side project Peccatum under the pseudonym Lord PZ (the other members of the band were Ihsahn and his wife Ihriel, who is also Solberg's sister).
Limited Special Collector's Ultimate Edition: Blood Music produced a vinyl box set of Emperor's work that served as this. It outdoes their previous Moonsorrow set as the largest metal retrospective ever produced, and includes a staggering twenty-four LPs and one 7" single. Part of this is because every single LP was pressed at 45 rpm, but they also went all-out and included everything the band ever recorded. (One could, however, argue that Neurot Recordings' Neurosis box set, Strength and Vision, outdid Emperor's box set for sheer scale, coming in at nineteen 33-rpm LPs and eleven CDs. There's more music on the Neurosis box set, but the Emperor box set still has more LPs in it.)