I don't quite understand the "not changed in sound" part.
AFAIK, "lox" came to English through Yiddish, which got the word from German. And in German, the vowel was always "a" not "o" (e.g. https://ia600301.us.archive.org/32/items/etymologisches00klu... traces the word to "lahs"), so the vowel quality and the final consonant appear to have changed.
AFAIK, "lox" came to English through Yiddish, which got the word from German. And in German, the vowel was always "a" not "o" (e.g. https://ia600301.us.archive.org/32/items/etymologisches00klu... traces the word to "lahs"), so the vowel quality and the final consonant appear to have changed.