Ever listened to Trans-Siberian Orchestra's "Beethoven's Last Night?" one of my favourite albums. Make sure you're watching/listening to the NARRATED version (TSO always narrates their concerts but this is the only album they've come out with with narration to my knowledge which is good because it makes ZERO sense without it).
I think this is it. I haven't listened to it yet but it's fantastic. And it's a great fit for this forum lol. All about Beethoven the night he dies and Mephistopheles and AGGGH so good. It's technically "rock opera" but incorporates a ton of Beethoven themes into the music.