I have an old Multiface 1, which I love to bits, but I can only use it with my old PC laptop. I'm now using a MacBook Pro and I can't use my old Multiface with it because it doesn't have a PCMCIA slot.

Now I have a Focusrite Sapphire Pro 24 that I use with my MacBook Pro, which I mostly got because I couldn't afford something as good as the Multiface.

What I'd like to try is taking a digital signal from the Focusrite into the RME while it's in stand-alone mode, and then taking the analog output from that to my speakers, bypassing my cheap mixer. I have a spare MIDI interface (Korg Nano Control) which I plan to use directly with the Multiface.

My question is whether this is worth doing. Firstly I'm assuming that the Multiface has better D/A convertors, which might not be right as the Focusrite is considerably newer. Then also, I'm not sure whether it would be best to use the optical or the coaxial connection. I read in a couple of places that the optical route requires the signal to be changed from digital into another form and then back again - which is not a problem - unless it's being changed from digital to analog and then into another form.

Any guidance or opinions on this would be appreciated.