Quite a few CD’s were pre-emphised, especially from Denon they had rising HF to lower the play back noise, bit like Dolby.
But to play these without them sounding bright, your CD player needed to have auto de-emphasis circuit to make it flat again.
https://forums.stevehoffman.tv/threads/pre-emphasis-list.121188/page-58
Bit more I think, maybe even 10db at the peak
Whats a few dB among friends...
Cheers George