The idea here lies on the idea that we haven't tapped yet into the full potential of the raspberry pi in terms of ADC.
Some have shown that the first gen of Raspberry could go to 10Msps as detailed here https://digibird1.wordpress.com/raspberry-pi-as-an-oscilloscope-10-msps/

My take is that the new Raspberry Pi.es (3 or even W) can surely go above. And I want to try it, either with this old CA3306E or with more recent kick-ass ADCs.
Let's see!