I'm looking to get audio from my mac powerbook to my Cambridge audio Azure DAC which is 7 metres away. I tried usb, but this only allows 16 bit. I just bought a 7.5 metre optical cable (Saturn series $30), but it keeps cutting out. Is there a signal strength problem out of the mac or is that too long for optical cable? Alternatively I could run 8 metre RCA's to the amp and place the DAC next to the laptop? I tried a wi fi setup but it was woeful with large music files. Dropped out a lot. I'm going a bit mad trying to solve this so any help would be awesome.