Hi Robin, was it on any games in particular? I can think of a few where this would happen purely from the nature of the effect you're trying to listen for.

No, just seems to happen, like an audio lag.

So I get that when using my iPad rather than my desktop. Not only when changing between the different options but during all audio playback. That seems more like an internet issue, as if it's struggling to steam the audio or as if it's trying to do real time sample rate conversion.

Your problem sounds more like what I mentioned in the previous comment. Games like Reverb Wizard, Distorted Reality and Dr. Compressor are likely to click/pop when changing between different sounds due to the tail/sustain that these effects add. If you chop a piece of audio before the tail has completely finished then that abrupt cut will cause a pop. It's why you have 'Create fades on clip edges' as an option in your DAW. I might be teaching you to suck eggs here (English idiom for those not in the UK) but those pops are a common occurrence when a loop isn't perfect. There are a fair few imperfect loops in the different sounds on here and you'll hear them at the loop point but the pops from chopped tails can work to your advantage. Click between the different options quickly on Reverb Wizard and if you hear a pop while changing, the reverb setting are different. It can easily help you identify which is the odd one out.

Thanks for the detailed explanation.