Kitzur shulchon oruch writes that wine and meat is not allowed at night but allowed immediately the next day (as it is a nidcheh this year)
Music is not mentioned AT ALL in shulchon oruch in connection with the 3 weeks or sefirah.
It does however say in Shulchan Oruch that music is not allowed ALL year from the time that the beis hamikdash was destroyed.
I know this is really old, but someone posted in the thread, making it pop up in my 'new replies' list, and I couldn't resist responding to this comment I must have missed originally. So Harry, if you happen to see this, here's my response:
I'm not sure why you had to go to the Kitzur. The Rama in Shulchan Aruch (558:1) says explicitly that on a nidche, meat and wine are asur till the morning (as opposed to till chatzos in most years). The Mishna Berurah there (558:4) says only meat and wine are asur till the morning, but bathing, laundering and haircutting are mutar right away (whereas in 558:3 he says they'd be asur till chatzos most years).
As far as music, the added issur of the 3 weeks over the rest of the year is brought down by many poskim. The lashon of the Mishna Berura (551:16) is "asur l'asos rikudin um'cholos m'yud zayin tammuz v'eileich" (this inyan is also found in the earlier poskim, though not in Shulchan Aruch). Poskei zmaneinu have differed in their application of this added issur to modern music consumption, but many people take on some level of stringency with regards to music during the 3 weeks. The question was whether this added stringency, which would certainly apply till chatzos during a regular year, is mutar immediately at night on a nidche. As I said, I saw in a likut sefer that it applies till chatzos, but there was no real mekor given.