I don't like it either, though I've read a lot of positive posts about people thinking it's great. Music taste is subjective though.. and one man's food is another man's poison.
But yeah, you can mod it all up. Go to..
Disciples III/Resources/Profiles/Music
Contains all the music files. There are two types. Ambience (amb) and Battle (battle). Numbered accordingly, and differentiated by faction type. They are in .ogg format. If you're looking for a very good, and free, audio convertor (and editor) check out
http://audacity.sourceforge.net/ I used this to convert .mp3 files to .ogg, but also to edit my battle music (instrumental battle stuff) and chained several songs together into 6-8 minute loop files; I found the current 3 minute loop gets repetitive in battle.
So, make your music files and plop them in the folder stated above. But you're not done yet.
Disciples III/System/DCSArenaEx.ini
Near the beginning are script commands which tell the game to load up the music files. Again, this is sorted by faction type. You can actually make a ton of music that exceeds the amount the game defaults at. The game selects music randomly from the script files.
Here is a cut and paste of what mine looks like to give you a sense of scale (don't mind the Russian acryllic.. I'm running off of their version). You'll see I have unique sounds for ambient (which paints a flavour), but I've opened up the battle music to be the same random palette across all matches. I think combat music is chosen based on your enemy's faction type, so in the end I decided to max out the versatility of the combat score.
//Èìïåðèÿ ãðóçèì íà âîðëä ìàï, êîãäà èãðàåì çà äàííóþ ðàñó empire
dcsmusic { file "resources\\music\\humans_amb1.ogg"; attr "worldmap"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_amb2.ogg"; attr "worldmap"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_amb3.ogg"; attr "worldmap"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_amb4.ogg"; attr "worldmap"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_amb5.ogg"; attr "worldmap"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_amb6.ogg"; attr "worldmap"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_amb7.ogg"; attr "worldmap"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_amb8.ogg"; attr "worldmap"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_amb9.ogg"; attr "worldmap"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_amb10.ogg"; attr "worldmap"; attr "Empire";}
//Ýëüôû ãðóçèì íà âîðëä ìàï, êîãäà èãðàåì çà äàííóþ ðàñó elves
dcsmusic { file "resources\\music\\elves_amb1.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb2.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb3.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb4.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb5.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb6.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb7.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb8.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb9.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb10.ogg"; attr "worldmap"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_amb11.ogg"; attr "worldmap"; attr "Elves";}
//Äåìîíû ãðóçèì íà âîðëä ìàï, êîãäà èãðàåì çà äàííóþ ðàñó legion
dcsmusic { file "resources\\music\\demon_amb1.ogg"; attr "worldmap"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_amb2.ogg"; attr "worldmap"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_amb3.ogg"; attr "worldmap"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_amb4.ogg"; attr "worldmap"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_amb5.ogg"; attr "worldmap"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_amb6.ogg"; attr "worldmap"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_amb7.ogg"; attr "worldmap"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_amb8.ogg"; attr "worldmap"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_amb9.ogg"; attr "worldmap"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_amb10.ogg"; attr "worldmap"; attr "Legions";}
//Íåæèòü ãðóçèì íà âîðëä ìàï, êîãäà èãðàåì çà äàííóþ ðàñó undead
dcsmusic { file "resources\\music\\undead_amb1.ogg"; attr "worldmap"; attr "Undead";}
dcsmusic { file "resources\\music\\undead_amb2.ogg"; attr "worldmap"; attr "Undead";}
dcsmusic { file "resources\\music\\undead_amb3.ogg"; attr "worldmap"; attr "Undead";}
dcsmusic { file "resources\\music\\undead_amb4.ogg"; attr "worldmap"; attr "Undead";}
dcsmusic { file "resources\\music\\undead_amb5.ogg"; attr "worldmap"; attr "Undead";}
dcsmusic { file "resources\\music\\undead_amb6.ogg"; attr "worldmap"; attr "Undead";}
dcsmusic { file "resources\\music\\undead_amb7.ogg"; attr "worldmap"; attr "Undead";}
dcsmusic { file "resources\\music\\undead_amb8.ogg"; attr "worldmap"; attr "Undead";}
dcsmusic { file "resources\\music\\undead_amb9.ogg"; attr "worldmap"; attr "Undead";}
dcsmusic { file "resources\\music\\undead_amb10.ogg"; attr "worldmap"; attr "Undead";}
//Ìóçûêà âî âðåìÿ áîÿ
//Ìóçûêà çàãðóæàåòñÿ è íà÷èíàåò èãðàòü êàê òîëüêî ïîÿâèëñÿ èíòåðôåéñ çàãðóçêè áîÿ
//Èìïåðèÿ ãðóçèì âî âðåìÿ áîÿ, êîãäà èãðàåì çà äàííóþ ðàñó empire
dcsmusic { file "resources\\music\\humans_battle1.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle2.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle3.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle4.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle5.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\elves_battle1.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle2.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle3.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle4.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle5.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\demon_battle1.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle2.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle3.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle4.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle5.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\Undead_Battle1.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle2.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle3.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle4.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle5.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle6.ogg"; attr "arena"; attr "Undead";}
//Ýëüôû ãðóçèì âî âðåìÿ áîÿ, êîãäà èãðàåì çà äàííóþ ðàñó elves
dcsmusic { file "resources\\music\\humans_battle1.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle2.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle3.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle4.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle5.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\elves_battle1.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle2.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle3.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle4.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle5.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\demon_battle1.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle2.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle3.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle4.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle5.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\Undead_Battle1.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle2.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle3.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle4.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle5.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle6.ogg"; attr "arena"; attr "Undead";}
//Äåìîíû ãðóçèì âî âðåìÿ áîÿ, êîãäà èãðàåì çà äàííóþ ðàñó demons
dcsmusic { file "resources\\music\\humans_battle1.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle2.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle3.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle4.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle5.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\elves_battle1.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle2.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle3.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle4.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle5.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\demon_battle1.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle2.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle3.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle4.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle5.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\Undead_Battle1.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle2.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle3.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle4.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle5.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle6.ogg"; attr "arena"; attr "Undead";}
//Íåæèòü ãðóçèì âî âðåìÿ áîÿ, êîãäà èãðàåì çà äàííóþ ðàñó undead
dcsmusic { file "resources\\music\\humans_battle1.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle2.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle3.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle4.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\humans_battle5.ogg"; attr "arena"; attr "Empire";}
dcsmusic { file "resources\\music\\elves_battle1.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle2.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle3.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle4.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\elves_battle5.ogg"; attr "arena"; attr "Elves";}
dcsmusic { file "resources\\music\\demon_battle1.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle2.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle3.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle4.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\demon_battle5.ogg"; attr "arena"; attr "Legions";}
dcsmusic { file "resources\\music\\Undead_Battle1.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle2.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle3.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle4.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle5.ogg"; attr "arena"; attr "Undead";}
dcsmusic { file "resources\\music\\Undead_battle6.ogg"; attr "arena"; attr "Undead";}