I've been playing with the ADC and scaler for a couple of weeks now. Thoroughly impressed.
I see a couple of posts above about the input impedance of the ADC. Interestingly I was going to comment on that topic, too.
Although I see why one wants to have high input impedance on testing equipment---i.e., to cover all kinds of DUT by providing essentially no load---, I do notice a disadvantage. Such high input impedance causes interconnect cables to be vulnerable to noise! Of course, in most cases the noise is way below audible levels. But these days we hobbyists measure these things not just from audibility concerns. We measure devices whose noise floors are extremely low.
For example, today I found that my very short (2 ft) Canare L-4E6S star quad balanced cables, used to connect a DAC to the Cosmos Scaler, was very finicky with their position (literally posture) relative to other cables. The effects were clearly shown on measurements---not a beautiful picture I'd like to see! Took some time to troubleshoot and finally find the culprit: the scaler's 200 kOhm input impedance. That made sense.
For testing modern devices, 10k - 20k Ohm should be high enough. I wish the scaler had selectable input impedance