That's great, thanks for the info. I was checking out reviews today and it's some machine.Basically the difference is that the gold one has been 'modded' which may improve the sound when used with its internal DAC/audio outs. If you use it as a transport only (into an external DAC) these mods don't come into play and so you'd be better with the silver version.
I'm currently using my silver one direct into my preamp (bypassing the Venus II) and it's a surprisingly good unit when used that way. Definitely not 'deficient' in any obvious way as compared to the the A6->Venus II option. I daresay a direct comparison might reveal subtle differences in favour of the £3k-ish DAC over the in-built one, but nothing jumps out when listening direct without a 'comparison hat' on. Caveat being that my ears aren't as good as they were and so differences between the two may be more obvious to others.