when humans perform music, no two notes sound exactly the same. why try to change that? All Felt Instruments libraries are based around a philosophy that music should be about getting the feel right, rather than creating a perfect, airbrushed version of sound. i Embrace the performance imperfections. I love them.
The instruments are sampled and processed using unobtanium hardware, mostly made between the 1940 and 1969. to preserve the tone, I don’t noise reduce the samples to death. So yes, some hiss is present. But so is the air and texture.
Of course, there are downsides to that approach. Some notes may be quieter or louder than you’d expect. Sometimes the timing might be slightly off. I think it adds a lot to the realism and character of the instruments, but if you’re looking for perfectly polished sounds - these are not for you.