I see you are struggling with a pre/pro decision because I saw your earlier post about purchsing a used pre/pro.
Having owned a REF20 and just purchased another one on here for $775, I would recommend the REF20. It is a straight forward unit without a lot of bells and whistles. Most importantly, it is upgradeable. The sound of the REF20 is warm to neutral. I have not heard the Sunfire so I cannot comment.
Please note that my primary pre/pro is a Theta CasaNova.
Good luck...
Having owned a REF20 and just purchased another one on here for $775, I would recommend the REF20. It is a straight forward unit without a lot of bells and whistles. Most importantly, it is upgradeable. The sound of the REF20 is warm to neutral. I have not heard the Sunfire so I cannot comment.
Please note that my primary pre/pro is a Theta CasaNova.
Good luck...