They are in two different DAC price and build quality levels. Apples and oranges. While I haven’t compared my NT-505 with the E30ii I can say that the NT-505 punches way above its weight class. I think I paid about $1,500 for mine new and I see they are selling used above $1,000 and the E30ii is selling below $200 used, if that means anything.
The NT-505 with the dual AK4497 chips was discontinued and replaced by the NT-505-X with dual ESS Technology ES9038 Q2M chips.