I have not tried the coaxial input, just optics. There is a very light background noise. By cons, if ever the fiber is disconnected, then the noise becomes. A little pity, I would have thought that in the abscence of any signal conversion would take place.
Also, if I plug a chain RCA and headphone jack, it created a background noise on the jack. A shame.
Overall, the sound quality is very good (well I use it on a TV to listen to broadcasts, not for listening to music).
I have been luckier than another buyer: the transformer no way heater (if connected 24/24, I put my hand on it while reading the other comment: it is cold).
