How can I "bump" my system clock by fractions of a second on macOS for ham radio time keeping needs?

I'm running Ventura 13.4 on an M2 MacBook Air. I run the FT8 and FT4 digital modes for ham radio. FT8/4 requires fairly accurate time synchronization. It seems that macOS gets out of sync when waking up from sleep. (See [Time.apple.com sync](https://discussions.apple.com/thread/254749768)) . The solution for better time synchronization is to run chrony, or better, the GUI version, chronyControl. (See [Accurate time keeping on an Apple Mac running macOS Big Sur for FT8, FT4 and WSPR](https://qso365.co.uk/2021/04/accurate-time-keeping-on-an-apple-mac-running-macos-big-sur-for-ft8-ft4-and-wspr/)) This has been working well for me, very well. My clock is very accurate. However, I'm still having time-shift issues. Notice that the [time.is](https://time.is/) website says my time is +-0.001 seconds. But look at the left-hand side, the third column is my time shift compared to others, the rest of the world is about 0.8 seconds off. ![Screenshot of two windows: the left window shows timings for FT8/FT4 while the right window is the current time according to the website time.is ][1] Since it is unlikely that the rest of the world is wrong, I must be wrong. Other hams have steered me to the likely culprit: I have an audio latency issue. The audio setup is simple and fixing it is unlikely. So I'd like to be able to bump my system clock by fractions of a second. (Clearly, I'll have to disable chronyControl when I do this!) Any sort of shell script to read the time and set the time would probably not work well since it would take a fraction of a second to run. I need a better way to do this. How can I bump my system clock by a specified amount?