Devialet adviced me to use a glass cleaning liquid and a soft microfiber cloth to remove the discolouration. Actually it worked very well.
Living room: Kii Three/BXT with Control.
Den: Tannoy Precision 8 iDP with TS112 iDP subwoofer.
In the cupboard, waiting for a sibling: 1st gen. Phantom Silver running DOS1
My Phantom Voyage
Den: Tannoy Precision 8 iDP with TS112 iDP subwoofer.
In the cupboard, waiting for a sibling: 1st gen. Phantom Silver running DOS1
My Phantom Voyage