It depends on the pop -
- if they are more or less continuous (while tracks are playing), you are playing at a volume near 100 and if it changes in character as the volume level is changed and goes away if the volume is lowered to below approx. 90 then it’s the bug in the FPGA code in Redcloud.
- If it’s not 1) above and if most SACDs play fine and a few don’t play right it might be that you have a SACD with the stereo section DST compressed (DST is a lossless compression designed to work with DSD that approx halves the size of files. It’s required for the multichannel section of SACDs but optional on the stereo section. It’s ususally only used on stereo sections of discs which are very long and hence need the compression.)
- if it’s not either of the above I’d try a different cable or input between the DMP and the DS, say a digital RCA or XLR or the other I2S input or an unrelated cable.
For 1) and 2) above it won’t happen with PCM (or at least the same thing won’t happen with PCM)