Is it possible to obtain 32 channels (single ended) of 16 bit AtoD conversion (15KSmps per channel), and set individual per-channel gain with onboard OPAMP in PGA mode?

[SD.11]

The idea is to change PGA gain before every conversion, but I can't find any info about the time that PGA needs to change the gain.

Manual states that it is possible to have up to 36 16bit channels of ADC. Manual states that PGA could be attached to ADC for signal amplitude optimization. Buy I can''t find if the PGA could be attached between the input pin multiplexer and ADC. And it is not clear how many external pins could be used for AtoD conversion.