Hi, everyone. I have an iMac 27'' Late 2013 and recently got Edifier Studio 7 (R2700) active acoustical speakers (two). The active speaker has Type-D digital amplifier. Thing is wired to Mac with Klotz FOPTM02 Optical Mini-jack to TOSLINK PVC cable of two meters. The thing is that if speakers are connected to computer and there a signal from out, there is a static noise from every channel on each speaker. It is quite silent but you can heart it. What can it be and how can I solve it if it's an issue?