I get this idea from my understanding of sound. I'll use my HiFiMan HE-300 as a "benchmark" To me, they seem slightly boosted in the mid bass, moderately boosted in the low-mids, neutral in the high-mids, and slightly recessed in the treble. Ideally, I would have a bit more recession in the topmost portion of the mid-range, but that might be attributed to the bright Schiit Modi/iBasso D-Zero.
Can anyone help me understand my tastes better? I'd like to be able to read a bunch of reviews and be able to know approximately how a headphone sounds. I thought I did but my experience with the Onkyos has really changed that.