Differential analogRead

[ScruffR]

I guess you have seen this post

Faster ADC sampling challenges (SPI, MCP3008)

I added photonAudio sample 4. I should stress that this is a proof-of-concept only and only sort of works. The main thing is that the code uses two ADCs (ADC1 and ADC2). They’re run in dual-simultaneous mode, so both are sampled at the same time. They’re also run in scan mode so multiple pins are sample sequentially, and very rapidly, 5 cycles of the ADC clock (30 MHz). ADC1 is set to read A0, A2, and A4. ADC2 is set to read A1, A3, and A5. 44100 times per second, controlled by a hardware …

Can you elaborate what you'd need beyond that approach?