I have USAA and do insure personal valuables. Yes, a diamond ring and earrings, watches...but it was too expensive to insure the audio at full replacement cost.. They will insure the audio as well but it does cost. My audio is covered under my general posessions along with tools, clothing, computers etc...
There is a deductible and you have to document everything. You will need pictures of your system and original receipts. They will try to depreciate it all. Call your insurance and discuss personal properties.
Someone mentioned companies by name above. You do get what you pay for. If you can afford Chubb they will be the best at replacement.