Even if we chant namabhasa, we can still experience a certain amount of bliss. We can even be elevated enough to attain Vaikuntha. But if we want to achieve the Lord’s full presence, imbued with our rasa or relationship with Him, and thus become qualified to enter into the topmost abode, Goloka Vrndavana, then we have to chant suddha-nama.
Lectures from a disciple, Vol 1, p. 182, Minsk, 5.19.2002