Some posts above, mine included, praise USAA. It's a member-owned company which ensures active duty military and veterans, their spouses and adult children. They are extremely easy to work with (phone or online) and have really decent rates.

With that said, the VPP I mentioned above is a rider on my USAA Household policy. In setting it up one can declare which/what personal property one wants on the rider, e.g., instruments, jewelry, guns, collections, etc. You set it up for one, some or all of the categories. In this way, you can choose to have 'only' the instruments insured by the rider.

Other companies may do the same. I don't know. As soon as I was eligible for USAA (the above membership wasn't always so wide ranging) I got it as soon as I could (auto, home, umbrella, riders, etc.). That was a few decades ago. ;)