Translation:We are ordering tickets for a classical music concert.
if музыка is in the genitive wouldn't it be музыкы?
No. We don't use ы after к in native Russian words -- it has to be ки.
(This is the opposite from, say, Slovak, where it is never ki and always ky. As far as I know, no Slavic language can have both i and y after g k kh -- they either always have i or always have y.)