Can you wear black dress socks with either a dark navy suit or a dark grey suit... or do socks have to match the color of the suit?

Socks can match either the shoes or the pants, both are fine. 

Everything is ok and i will choose the grey suit.

Black socks are absolutely fine with ANY suit except brown, or any pale colour.

They are GHASTLY with white.

Black is fine with all those choices

Socks can match either the shoe or the trousers, for men. Women have far more latitude.

I'd wear black.

Nobody has enough of an assortment of socks to match a blue or grey suit, no its fine.

Black dress socks traditionally go with all dark suits, except a brown suit.

Socks can match either the shoe or the trousers, for men. Women have far more latitude.

who says you can't............