You can notice (bad measurements == bad sound) when something’s really wrong:
- Severely mismatched triodes and/or tubes (north of ~ 25 - 30%)
- Extremely weak or below nominal results (transconductance)
- Consistently noisy tubes (microphonics and intermittent noise you just have to use your ears)
If you want to compare NOS or extremely strong testing tubes versus much less strong testing tubes - the latter will (probably) not last as long as the former in service, but will generally sound just as good (if not better), and may still last a long time.
If your matchings (triodes, tubes) are within say 10% or better, don’t worry about it beyond that. In the past I’ve bought super premium matched / tested / noise-selected / cryo / curve-matched / brawndo enhanced / etc tubes before, and found NO difference to just decently-testing tubes. Yes it can be dependent on the component & slot you’re plugging them into - but usually not that much. I’ve never needed better than Upscal’es "Platinum Grade" screening and testings service. I also like to buy new production power tubes that have been burned in a bit before matching (to screen out early failures).