I flew out here on September 8th with BA, and there was absolutely no chance of taking any of my records onto the plane as hand luggage.
I ended up couriering them over, signed delivery in three padded boxes. They arrived safely the next day. No way were they going in the hold.
And they're also extremely strict at immigration at the moment. If you intend to play, you're not native US, and don't have a visa, and they catch you....they will send you straight back on the next plane. LA is probably the strictest US airport I've come across.