A diffusor does not absorb the incident sound but it reflects it in as many directions as possible so that the sound field becomes more even, i.e. more diffuse. Deployment of diffusors for optimising the interior acoustics is always a good idea when the proportion of diffuse sound is to be increased without the use of absorption measures.
Listening rooms with very low reverberation times are often perceived as too „dry“ and „acoustically dead“. Studio and concert rooms also greatly benefit from the lively and open sound of good diffusors. In home theatre projects we ofen use diffusor modules to support the „encasement“ by the surround channels.