me too, i love retro games and i always get inspired by them. it is amazing how they could archive such cool games on low end computers like the c64 (that i had when i was 6-7 years old)
never had an issue with sound when using libgdx!
i could not see any difference between using libgdx on android and spritekit on ios devices so i cannot confirm that either. i had no issues with touches or sound in my games.
can you share what game you are working on? it is interesting.
at the top of my list of games i wanna re-make is "Bruce Lee for C64"
watching this video brings memories back ?