Who the hell are these Mussorgsky and Tchaikovsky??!!... I can't find them in the IMDB - a.k.a. the Bible. They must be insignificant, let alone be Oscar winners like our Hans - the Prophet - Zimmer.
And where did you get these movies, Pictures or other, Night on Bald Mountain... Are these artsy-fartsy Euro-cult flicks? They're not in the IMDB either... Are you sure you didn't mean Night on Bareback Mountain? That would be more like it and appropriate since that film did get an Academy Award for Best (sic) Original (sic sic sic) Score. Those films you mention probably stank! Music and all... Their directors should have known better and hire ex-hiphop/trance/jungle/rave/urban........ DJs/producers to score them; those guys really breathe originality into anything they scratch, loop, filter, and touch (automate). Look what they did for TRON 2!