This is described as radha-bhava-dyuti-suvalitam naumi krsna-svarupam. Lord Sri Krsna was absorbed in the features of Srimati Radharani. This was disclosed to Ramananda Raya when he saw Lord Sri Caitanya Mahaprabhu. An advanced devotee can understand sri-krsna-caitanya, radha-krsna nahe anya. Sri Caitanya Mahaprabhu, being a combination of Krsna and Radha, is nondifferent from Radha-Krsna combined. This is explained by Svarupa Damodara Gosvami:

Radha-Krsna is one. Radha-Krsna is Krsna and Krsna's pleasure potency combined. When Krsna exhibits His pleasure potency, He appears to be two-Radha and Krsna. Otherwise, Radha and Krsna are one. This oneness may be perceived by advanced devotees through the grace of Sri Caitanya Mahaprabhu. This was the case with Ramananda Raya. One may aspire to attain such a position, but one should not try to imitate the maha-bhagavata.