The ADuC7061 is not totally clear about the effect of channel changes. Up to now, on other devices, we've discarded the first few samples after changing channel. Does the ADuC7061 insert a delay of it's own when channel changing? (apart from the 60uS one).
When changing channel on the primary ADC and then skipping 3 samples and using the 4th, I'm getting about half the theoretical conversion rate. I'm also using the secondary ADC on a similar basis - I'm aware that there may be resynch between the 2 ADC's when doing this.