I guess we're getting into perceptions and semantics then, because unless you have a broken set of headphones, the charts are accurate. :/
It depends on how you perceive and define the word "bass". If you're talking about what I would refer to as "
rumble", then I'd agree that the Senns are more "bass"-heavy.
However, I mostly agree with the chart's definition of bass as extending to mostly 180-200ish Hz, and by that definition of "bass", the M50s are definitely more bass-heavy.
If you picked trap music and/or dubstep for your sample selection, that might skew your interpretation
(as many songs in these styles bury their "bass" drums and instruments into the very lowest frequencies). Perhaps the lack of contrast by a reduced "air" band is making you feel that they're more bass-heavy
(comparing bass to "sparkle/air" band rather than to mids).
-Ki
Salem Beats