Have just decided to update my hi-fi system by purchase of Marantz PM6006 amplifier, I was attracted to this model due to it having 2 optical connections for my 4K LG43UF68OV Smart tv and Technics SL-PG500A cd player, the tv now plays through hi-fi, except when selecting a You Tube video, it will only play through tv speakers, and the optical blue light is flashing on the amplifier, most annoying, any ideas to the cause?