When you are searching for potential sources of backlinks. Is page authority or domain authority more important for search engines?
I think page authority is more important for search engines in general because they analyze precisely the page from the backlinks come. But of course, page authority depends on domain authority.
However, page or domain authority is a subjective and predefined factors notion. Each search engines or site of backlinks analysis (like Open Site Explorer from Moz or Ahrefs) have a definition of authority.
A factor of authority can be important for one search engine and less important for another. That's why it's hard to say if authority is in general an accurate factor to take into account for SEO. It's more reliable to talk about a specific factor for one specific search engine.