Just did a quick test.
I opened up a fresh project and did everything on the stereo out bus I had before and there isn’t even a hint of noise. So it isn’t inherent to those plug-ins.
I then added an audio track, put Amp Rack on it and selected a noisy preset and started monitoring. This created some noise, but it was distinct from the earlier hiss in both sound and audio spectrum, wasn’t nearly as prominent and went away entirely when I chose a different preset. In the defective project, even muting the Amp tracks doesn’t remove the wind noise. And the noise was there before even when not monitoring.
That’s it so far. Obviously a new project doesn’t drag much on the CPU, so that needs to get tested by adding tracks and paying close attention to what happens after each one and each new plug-in. We’ll see how it goes.