It's strange.I am 100% sure about the brightness in the beginning.I mailed Steve about it.It was exactly like i wrote before.
From 0-300 hours the bass got deeper,with bigger punch,and simply more present overall.
High frequencies lost the "metallic hiss" that was there in the beginning.They got more natural.
Midrange was excellent at 0 hours,but also improved with time.
Dimensionality and harmonic structure improved greatly.The whole sound became more musical and coherent.
The biggest changes were from 220- 250 hours.
Soundstage is excellent now.But i haven't kept any record of how it changed as hours passed.