gancanjam
100+ Head-Fier
I've had the fa-12 and fa-10 side by side. If you have hard to drive planars the fa-10 will power them gloriously meaning full dynamics and soundstage. The fa-10 treble is more laid back which would work well with brighter headphones like some hifiman, otherwise get a the fa-10 pro for dark headphones and/or avoid warm dacs.
Fa-12 is slightly richer than the fa-10 in the lower mids. Fa-12 is a fiery sound, fa-10 is an earthy sound.
A new term ! "Earthy" is a Scent-ophile (?) term than an Audiophile term ..LOL .. It certainly can resonate with audience though ! Especially pairing FA-10 with warmer HPs gives that "grounded" a.k.a. Earthy vibe