Only allow Admins to post comments

I have not found any posts newer than 4 years old on this subject, but I apologize if I missed any more recent ones.

I would like to only allow Administrators (or any role higher than subscriber) to post comments. Subscribers would be able to read the comments, however they would not be able to respond.

I have tried various Role Management plugins, but have not found any that specifically control who can post comments. I am trying to setup a web comic and would like only the comic authors (a.k.a. the three administrators) to be able to leave comments on the comic posts. We want to limit all discussions to a message board, which is why I don’t disable user registration.

Currently running Comicpress 1.4.9.10
I tried the “Role Scoper” and “Role Manager” plug ins, but the didn’t help.

Thank you for any help you can give, I am at my wit’s end.