Hello, I liked the Koss KPH30i Headphones sound better by example.
No idea for gsp 300, I cannot help, sorry.
I own a pair of Sennheiser momentum on ear, and I have yet found nothing that competes in punch on the whole spectrum for use with a phone. No amp needed, nearly undestructible and a sound that leaves you jaw open in pure bliss. Funny enough they seem unknown arround here.
I use them as reference. Compared to these, the musical...