I've asked this question of my insurance provider every year (USAA) and when I explored other options (I do so every few years). I have been told multiple times my audio equipment (unless it's pro-audio equipment I use for a business) is personal property and to keep documentation.
@elevick I recommend you call USAA again. I've talked to them multiple times and have been told it's part of personal property and I have high value property for my watches. I even shared replacing my stereo if destroyed would be equivalent to buying a nice car and the question raised do I want add the percentage coverage for my personal property.