There is the classic BBC dip which literally means it will be quieter in the midrange.A dip in the 1KHz - 3KHz range does not necessarily mean "loss of details". It just means that the upper mid (such as female voice) will be less forward. "Details" is more intrinsic to the resolution of the equipment and not really related to the frequency response of the speakers. A "BBC dip" only modifies the characteristic of the sound reproduction and not the details.
There are speakers that intentionally emphasize the "BBC region" and high frequencies and sometimes that may be mis-interpreted as "details".