Il gagne à être connu = He improves upon acquaintance.
Je ne le connais ni d’Ève ni d’Adam = I do not know him from Adam.
Je ne le connais ni de près ni de loin = I do not know him at all.
En chiffres connus = In plain figures.
Vous y connaissez-vous en vins? = Are you a judge of wine?
Je m’y connais = I understand all about it; I am an authority on it.
Connu! (fam.) = That is an old tale.
Je la connais, celle-là (pop.) = That is nothing new; I’ve been “had” before.
Conseil
*À parti pris pas de conseil = Advice is useless to one who has made up his mind.