Reread my post, Zipur. We agree 100% that recreational listening people want a 'colored / non flat' sound - the "V" sound you're referring to. I do too. But a mixing engineering needs flat listening so they don't make wrong mixing choices thinking there's too much bass and highs which is what a V sound tells you.
It is also important to have at least dual driver for in ears if you want to hear well. But I would disagree that all cup earphones are better for accurate listening. With the invention of dual and tri driver in ear buds - they have the potential to be even better than cup earphones since they block out all sound but the source material and because most cup earphones have only 1 driver.