cover comparison site

Hi all, does anyone know of somewhere you can go and get feedback on covers? I do not use FB at all and would only have friends giving feedback. I did testing with my audience and got good feedback on it, but it has not been working on Amazon. Also, everyone who sees the cover ‘in the flesh’ really likes it, and again this is cold groups, but it is not converting on Amazon ads. I wondered if there was a site you can go to to get feedback? Thanks so much.