Hi @Craig3,
Airbnb insurance will not cover your broken sound system but since you have a security deposit, you can make a claim through the Resolution Center against the guest within 48 hours after checkout. If successful, Airbnb will take money from the security deposit and send it to you. You will however need to provide documentation and if the guest does not agree, Airbnb decides.
To make the claim through the resolution center, you can check out this post: https://community.airbnb.com/t5/General-Hosting/The-Resolution-Center-A-How-To-Guide-Request-or-Offe...
Dave
David
Superhost Ambassador ~ Host Club Community Leader ~ Community Expert ~ Experienced Co-Host