Hi Francesco,
Your understanding is correct. If you just need two channels, then use one channel from ADC0 and other from ADC1. In that case, same code would work, but you need to enable secondary channel of SPORT as follow:
*pSPORT1_RCR2 = SLEN(13) | RXSE;
The received data will be interleaved in the RX_BUFF: primary (A1) - Secondary (B1) - primary (A1) - Secondary (B1)- ...... and so on. If required, you can put A1 data in continuously in one sub-buffer and B1 data in another sub-buffer. You need to configure DMA in 2-D mode with XCNT = 2, XMOD = (BUFF_SIZE/2) * 2, YCNT = BUFF_SIZE/2 and YMOD = - ((BUFF_SIZE/2) * 2) + 2
With this primary data would start from start of buffer and secondary data would start from mid of the buffer.
Let me know if you need more details.
--Prashant