HDMI is a pretty bad fit for connecting a preamp and an amp. A more generic, less encumbered format would be a far better choice--firewire or USB, perhaps. You don't need a video channel for such a connection. Also, I'm not certain how the digital amp in the A1400 works--does it have a A/D converter on the input side and a D/A converter on the output side? Or are we talking about completely different tech here?

I am the Doctor, and THIS... is my SPOON!