No idea which one is default atom
I am using probably gold since a year (the paint is long gone).
Midbass brings distorted guitars forward, especially with death metal, which is usually downtuned to C or A - this is the reason I like Xe6 so much and it's my daily since a year.
I don't have an impression something is "blurring" and my ears are trained with various music
(I have RME FireFace and Genelec monitors on my desk at work so I am also familiar with more flatten, closer to "reference" sound).
Xe6 can do good old Iron Maiden and Meshuggah 8-string wall of sound.
Ofcourse this is a matter of a taste / personal impression.
And seriously - I wouldn't classify Xe6 as basshead IEM.
I was hoping it is, but it's not.
It's warm, thanks to the great midbass probably no other IEM has, but there is not much sub.
FatFREQ Maestro SE could be considered basshead, or Legend X.
But I didn't liked them with metal - guitars were too laid back compared to Xe6.