What are Halachik reasons that some Poskim allow recorded music during the Omer, but others forbid all music?
Rav Hutner allowed it because he felt there is no real true simcha from taped music that will bring you to dancing and since that is the reason for the Issur he allowed it during sefira. By extension of the same logic Reb Shlomo Zalman in his sefer on Pesach allows Chazunis and classical music too; of course he adds it is better to be stringent. Reb Pinchas Schinberg has the most intriguing approach and basically says that today most people are in depressive moods and need the music as a refuah so therefore there is no Issur ever. Just an interesting extension of the music on sefias Haomer I saw recently that Reb Sternbach does not allow acapella music but allows music for exercising.