Since the version 1.7.1 Phantom firmware and the 1.5 version of Spark, you may hear occasionally some crackling sounds when playing via your optical.
This is a bug we identified with our customer's help and our dev team are working to solve in a near futur.
This happen only when you are playing via Optical via the Optical entry of your Dialog.
Note: There is an available workaround that can avoid this issue the time we solve it with an firmware update. We suggest to plugg your optical cable into a Phantom optical entry. The issue will not appear this way. If you are in a Phantom DUO setup, the sound will still be played on your both Phantom because the Dialog will dispatch the stereo even if the sound signal is firstly send to a Phantom.
Products: Phantom | Version: 1.7.1 firmware
Setup: Solo, Duo or Multi-room | Source type: Optical
Creation date: 03/08/2016 | KB article ID: PH02013