It seems that all my ZP IP addresses changed a few weeks ago and since then the Sonos plugin has been throwing hundreds of lines of errors. I tried everything, but what I really needed to do was get into the plugin config.
Here's the problem -
Because there were no valid ZPs listed in the config, the plugin config refused to load. So I was in catch 22 (can't get to broken config page to fix config, because the config was broken).
There should be a fix to this. Can plugin config pages be edited when plugins are disabled?