You won't see this sort of thing much anymore; Litvish rabbinic approbations in a Karaite's magnum opus.

Below are some images from the book Avne Zikaron (Vilna, 1872) by the notable Karaite scholar Abraham Firkowicz.

Title page:



The author (1786-1874):



The book included facsimiles of medieval Crimean tombstones. Here's a sample:

The subscriber list includes R. Shmuel Strashun (the Rashash):



and among the approbations is the following letter from R. Raphael Nathan Nata Rabbinowich, compiler/ author of Didkduke Sofrim (incl. Maamar al ha-defasat ha-Talmud):



There's even one from a Soloveitchik, this one with a famous family first name: