this can lead to unpleasant crackles and peaks in your audio exports. in order to reproduce the issue do the following:
create an empty project
create a sampler track
load a sample (f.e. a gentle rhodes melody)
move the start point of the sample to its center, so that the sound starts abruptly
activate a fade-in for the sample (length: e.g. 2 seconds)
put vst amp rack on the track as insert effect (preset e.g. california inn)
make a short recording of a few bars that contains 4 notes
export the project and listen to the audio
you will notice that the first sound from the sympler track cracks because the fade-in does not work. only the later sounds are captured by the fade-in and sound as desired.
I haven’t tried here on my side. But as far as I know, lots of VST Amp Rack presets are using heavy compressors, which could affect the sound dramatically. The “cracks” could be switching the compressor On and Off.
Thanks, Martin. It is true that VST Amp Rack at least amplifies the problem and makes it even more audible, but the basic problem is - I think - in the sampler track, not in the plug-in. I’ll give it another try, though. Thanks for pointing this out.