OK so that achieved nothing.  I've tried the amp and still the signal is scratchy to non existent. Is it possible to extract 24 bt sound from a mac?  I'm starting to think not, unless the computer is within a foot of the receiver or dac. Optical is pretty flimsy in my experience to date.

Right that's what I was hoping, no degradation. Being a digital signal it can't be effected too much, especially by a 15 buck device? It'll be here within the week so we'll see. Cheers for your help.

I tried a short (about a foot) optical cable and it worked fine, so I've been thinking either the distance or poor quality of the cable would be the reason (although it's seems decent enough).  My instinct was not to run the analogue that far so I appreciate your emphatic no.  Finally my DAC...

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...