I think Alpha 9 to A85 would be a side step at best. The Alpha 9 was a very good amp and time hasn't changed that. For a proper upgrade I'd suggest seeking out an A32 instead - superb amp, if you like the Arcam sound.
The 685s are still excellent speakers but I'm not sure they are the best match for Arcam (I never really got on with the combination). Certainly worth a try, but I'd be looking at some MA RX1s instead, particularly if you like MA's presentation.