Thanks, I will change it. The reason for the LMH6702 according to the datasheet of the ADC1175 is that it can drive dynamic capacitance at high speed. But I agree, for a few MHz analog bandwidth and 10 MHz sampling rate, maybe it is overkill. Which normal 50 MHz voltage OpAmp would you recommend, that can drive the dynamic capacitance of the ADC? The datasheet says, the ADC input jumps from 4 pF to 11 pF and back when changing the clock level.
Another question: the voltage supply for the ADC1175 has some strange arrangement with a ferrite bead, and they say the 5V supply has to be clean. But the voltage supply would be from 5V USB power from a PC, so I guess not very clean, which is the reason that I didn't even bother with the ferrite bead. But I don't mind if I get only like 5 or 6 bits effective resolution. Would this be possible? Or is there a way to make the 5V USB power a bit "cleaner"?
I think I will change the circuit to use individual modules for each input stage with input and ADC, connected with pin headers to a base board. Then I can build just one board first and the other boards when it works. And the individual modules could be used for other projects as well. Or I could even design a base board for 8 modules (I would need a fast 3-to-8 de-mux IC then, best with break-before-make outputs, to drive the many OE inputs), and only populate as many as I need.