If you replace the reddit.com domain in the searchbar for a libreddit instance you can access the content without an account

I currently use:

l.opnxng.com libreddit.privacydev.net libreddit.hu

For a more permanent approach if using firefox there exists an extension called libredirect that replaces automatically the domain

Finally, remember that some instances can be rate limited because of the current api pricing in reddit, you'll gave to choose another one or reload until it works

Hope this helps

Good point. A lot of Reddit audio links have been breaking or requiring logins lately. Are you running into this with specific posts or across the board? Might help figure out a workaround.