Airbnb solved this issue by using both online and offline indicators.
However, for your product, this seems a bit excessive but will solve the identity issue.
You can require people to link to their social media accounts such as Facebook & Twitter. This would even open up possibilities in the future to allow your site to scrap info from their feeds or say auto-post tweets/posts.
This is not really offline - but uses offline information. There are a couple of approaches. You can require a government ID or ask a series of questions based on publicly known information.
I am not sure what risk you are trying to mitigate. If someone misrepresents their identity, then they are committing fraud and your terms of service can address this.
I would just build in the ability to verify an account with a link to a social media site like facebook or twitter. Require that these social accounts be active (say 3 posts in last 30 days). This would provide some assurance.
You can then publish a dispute process that allows any legitimate band to notify you of potential fraud.
This provides reasonable and automated identify verification without spending tons of effort in fixing a problem that you don't actually have (yet).