I have a Male Siskin and 3 weeks ago added a Male European GoldFinch to the family

Siskin is comfortable as he has been around for a long time, the EGF just got introduced and his cage is placed high and the food is correct he is behaving normal just not whistling, shall i place them far from each other so they do not hear each other, might that help or is the reason that the EGF needs to adapt the new home ? Thanks again...