I fully understand that what im about to write people are going to laugh and make harsh rude comments so here it goes.... If mattress has a standard scale rating of 1 thru 10 1 being the cloud soft to 10 concrete floor.. Now if the audio HiFI world could adapt a standard scale like mattress i think it would help not only new people but everyone else ..the scale would be 1 being extremely warm... 5 being neutral....10 sterile,analytical. so when these youtubers are reviewing gear they can be held to something beside just there word and how many of us bought something they recommended and it was nothing like they said it was.. so with the scale rating system i think we could have a better understanding and wont have as much buyer's remorse.. As bigty was saying when you read the topping L70 amp is slight warm sound .. wouldn't be easier to say the topping L70 is on the scale of 4 to 5 depends on your headphones ... and thats the other thing that the industray has to do is to make the headphones adapt this scale also so it would be eaiser for new people and others to match it to the right amp and dac system .. because how many of us bought a amp recommend and paired it to your headphones and the treble was harsh, bright, sibilance issue... so would it be eaiser to have a scale that read product A headphones was scale to 7 that way we knew that they would work with what we got or they would not work at all and we need to look at something else... so this debate of warm sounding,neutral sounding,bright sounding would be eaiser for everyone to understand and buying gear more simple .
I can see the thought behind this, but as
@staticV3 says it's a tall order if not impossible.
First you'd have to get people to agree on what actual characteristics of the signal are "warm" and which are "analytical" or "sterile". We have not made a lot of progress on that in the past 30 years.
Next you'd have to quantify their impact on how much they make people perceive warmth, etc. Doable but would take serious testing, which nobody is eager to pay for.
Lastly you'd need to get manufacturers to test their own equipment against these standards and publish the ratings. Some manufacturers are allergic to testing of this nature because their gear isn't as good as they'd like you to think.
But actually, doing all of this would achieve essentially nothing.
The real bottom line is this: Amps, Dacs, and electronics in general are not supposed to be warm, sterile, or anything like that. They're supposed to be "straight wires with gain" with no sound of their own, and in fact many of them basically are. We call it "transparent to the source" and today most good gear is, in most usage scenarios.
The reviewers who give them subjective ratings on tonality are almost always hearing the results of cognitive biases, not the gear itself.
As StaticV3 said, 99.9% of these heard differences will go away in blind testing because they're not caused by the gear. The remaining 0.1% is not worth worrying about in the least.