As someone who unfortunately has experience in this arena (our home and business burned to the ground in the 2018 Camp Fire), I can tell you that it is *much* easier to make a claim when you have a separate rider on your homeowners insurance policy than when it's bundled into the homeowners policy. The rider you set at the actual cost of the instrument is paid without question at that set amount.
At policy writing you must supply receipt to set that value and it goes through Underwriting for confirmation--they fussed a bit the first time at State Farm when I put in my first Moore Bettah; 'guess they didn't think "a mere ukulele" could cost that much...
Because we had multiple policies in effect at the time of the fire, I can assure you that the musical instruments portion of the standard homeowners is questioned in much more detail, and in most cases, the maximum coverage is then depreciated. As well as the "musical instruments" likely includes other possessions and you'll very quickly reach that limit and be out of luck. Very quickly, I repeat. I had the "expensive" instruments on the rider and the more "standard" instruments as part of my "personal possessions."
My insurance going forward has *all* of my musical instruments (including cases) as a separate rider. Also ensure that you have an inflation clause in your rider.