> In that case you can serve both input and output within the same IO callback, thus the playthrough latency will be only a single period. By playthrough laten

> In that case you can serve both input and output within the same IO callback, thus the playthrough latency will be only a single period. By playthrough latency, do you mean having the output play the same audio being captured from the input/mic? One period of loopback/playthrough latency is only possible if you can instantaneously copy data from the input to output buffers (for example by using the same hardware buffer for both?). In practice, PipeWire and JACK2 both introduce 2 periods (in PipeWire, quantums) of buffering latency, which I've discussed in my blog (https://nyanpasu64.gitlab.io/blog/low-latency-audio-output-duplex-alsa/ https://nyanpasu64.gitlab.io/blog/low-latency-audio-output-d...), or you can confirm by reading their source code.