daasyochid: actually, I said very clearly that I felt that live music could be prohibited because it has a sense of extra simcha and I could stomach the chumro. I did argue about recordings and your second assumption is therefore correct too.
But the basic question remains. There is no indication that the geonim or the rishonim added music- even live music- to the “aveilus” of sefira. This only started about two hundred years ago (if Sam2’s assumption about the pri megodim is right) and so, why? why add extra aveilus? I do not understand why.
BTW- i do belong to the chassidische world that is quite meikel in aveilus ,as the halacha would be.