OK, that changes everything, I have assumed similar noise floor like Wavelabs test tone gen.which gives only -144db...I apologies
but still your test tells exactly nothing about plugins resampling quality which is very important if you work at 44,1kHz and use included Waves IRs /96kHz/
completely not true: it exhibits same noise as original file, when only single sample/dirac/ is processed...like you hopefully did...or even worse it translate into ugly fake reverb, when countinous audio is processed...
to sum it up-any noise inside IRs alwys adds artifacts to your audio and I have NEVER stated that it doesn't add anything