Thanks, then I can rule out the SDRAM as the cause.
I haven't been playing any videos yet, only streaming audio. I think I'll describe it more thoroughly, and perhaps we will be able to rule out even more causes.
I'm streaming AAC 320 kbit/s, using omxplayer. Listening to local files does make the pops and clicks less common, but they're not absent. I'd like to correct my previous statement regarding the frequency of the artifacts and say that they occur between 3 and 6 times per minute while streaming, while playing local files that number is between 1 and 3. The pops vary in loudness and channel, sometimes they're in the left channel only, other times in the right and sometimes in both. The loudness varies from loud (I'd say about -9 dB) to quiet (can't really give a number, but quiet enough that you're able to miss it if not paying attention). This only happens when using the new implementation. Switching to the old way makes the pops disappear.