The most common cause of sibilance is that it's embedded in the recording due to vocalist technique, non-optimal microphone choice or positioning. Sibilant sounds are a normal part of speech and are characterized by louder than average sound centered around 8kHz.
For music playback a key element for not making sibilance any worse than what's already on the record is to use equipment that can properly handle transients at various SPLs. That's a non-trivial task. Speakers that have off axis peaks in the sibilant range should also be avoided.
For music playback a key element for not making sibilance any worse than what's already on the record is to use equipment that can properly handle transients at various SPLs. That's a non-trivial task. Speakers that have off axis peaks in the sibilant range should also be avoided.