From today's OU Kosher Halacha Yomis
Q. When do all the restrictions of the Three Weeks and the Nine Days end this year?
A. Normally, all restrictions of the Three Weeks and the Nine Days remain in place until the tenth of Av at Chatzos (midday) because the Bais Hamikdash continued to be engulfed in flames on the tenth of Av (Rama OC 558:1). This year, since the ninth of Av falls on Shabbos when we may not fast, the fast of Tisha B'Av is postponed to Sunday, the tenth of Av. Sunday evening is the 11th of Av and therefore, the restrictions against taking haircuts, shaving, doing laundry, bathing, swimming, saying Shehecheyanu and sewing are lifted immediately at the end of the fast without waiting until the next day (Mishna Berura 558:4).
Nonetheless, eating meat and drinking wine (which are foods used for celebrations) are only permitted Monday morning after the fast this year, but may not be consumed Sunday evening. Since the day was spent in mourning, it is not proper to resume conduct of simcha (joy) by eating meat and drinking wine immediately after the fast is over (Rama ibid).
It is questionable whether we can play and listen to music Sunday evening, this year. Is music, which is used for simcha, treated like meat and wine, which are restricted at night and not permitted until the morning? Or do we consider music as less significant, and it is permitted immediately after the fast, similar to haircuts, laundry and bathing? (See Kitzur Hilchos Bein HaMetzarim p. 32:3 who prohibits and the sefer Pesach V'Tisha B'Av B'Shabbos p. 154-155 who permits). Rav Schachter, shlit"a paskened that when Tisha B'Av is postponed, playing or listening to music is permitted right after the fast is over.