I just moved and insurance

As others have stated,, Stereo equipment is covered under your Homeowners policy with no special endorsement. To make sure read the sections of your policy entitled "special limits on covered property". This is where you will find limits on jewelry, firearms, etc. Stereo equipment will usually not be listed here.

Just be aware that most policies will insure "replacement" value, not new value. Basically saying it will pay you for used market value

@elrod Sorry, wrong. Most policies have a full replacement cost endorsement for personal property. Most agents will add it routinely. Just ask to make sure you have it.

As far as payment, most company’s will pay the actual cash value (used price) first. Once the item is actually replaced with a new replacement, the difference will be paid. This is the general procedure, but can vary from state to state. Bottom line, if you have the replacement cost endorsement, you get paid full replacement cost as long as you actually replace the item. If the item is no longer available, you can replace it with something of equal functionality. 

Do you get your audio advice from an insurance forum?  Home/Property insurance is regulated at the State level, therefore, seek out the advice from a licensed agent in your home state. 

Testpilot, true. My comments above are based on 35 years in the insurance industry. I mentioned checking with your agent in the first paragraph.