All this little mini-mod idea does is replace some vanilla music that plays in the background, with the Gramophone songs played in the trenches of the maps. I did not want to replace all the vanilla music as there are only eight songs and I can't spend a lot of time on this so I whipped this up quickly while playing Iron Europe today.
strauss_radetzky_march.ogg -> ie_gramm_la_toussaint_rouge.ogg
beethoven_symphony_no_9_movement_4.ogg -> ie_gramm_le_chant_du_depart.ogg
franz_schubert_marche_militaire.ogg -> ie_gramm_minuit_chretiens.ogg
mozart_great_mass_gloria.ogg -> ie_gramm_la_marseillaise_chantee.ogg
bizet_carmen_toreador.ogg -> ie_gramm_die_watch_am_rhein.ogg
wagner_ride_of_the_valkyries.ogg -> ie_gramm_pariser_einzugsmarsch.ogg
beethoven_symphony_5_1.ogg -> ie_gramm_heil_dir_im_siegerkranz.ogg
dvorak_symphony_9_4.ogg -> ie_gramm_argonnerwald_um_mitternacht.ogg
Download Linkhttps://drive.google.com/file/d/0B_XEt5J8_HVnNHNyZy1KYkppd3M/edit?usp=sharingOnce downloaded, simply copy and paste the files in the Music folder into /Modules/Iron Europe/Music sub folder and overwrite by replacing.
If you want to keep the vanilla tracks you can retrieve them from regular Napoleonic Wars Music folder, the list of songs above as reference.