The improvement in knowledge and detachment can be perceived by devotees as an actual experience. Lord Sri Caitanya Mahaprabhu strongly recommended this process of hearing from a bona fide devotee, and by following this process one can achieve the highest result, conquering all other methods.

(S.B. 3.5.42)

Lord Caitanya, therefore, approved the process of hearing from realized devotees about the pastimes of the Lord. It does not matter to what category of this world the audience belongs. If one meekly and submissively hears about the activities of the Lord from a realized soul, he will be able to conquer the Supreme Personality of Godhead, who is unconquerable by any other process. Hearing or associating with devotees is the most important function for self-realization.

(S.B. 3.25.27)

The process of hearing from a pure devotee is recommended in all Vedic scriptures, especially by Lord Caitanya Mahaprabhu. One may stay in his position of life--it does not matter what it is--but if one hears from the mouth of a pure devotee, he gradually comes to the understanding of his relationship with the Lord and thus engages in His loving service, and his life becomes completely perfect. Therefore, this process of hearing from the mouth of a pure devotee is very important for making progress in the line of spiritual understanding.

(S.B. 4.20.25)

Sri Caitanya Mahaprabhu also recommended this process of hearing as a means of self-realization in the present age of Kali. In this age it is very difficult to follow thoroughly the regulative principles and studies of the Vedas which were formerly recommended. However, if one gives aural reception to the sound vibrated by great devotees and acaryas, that alone will give him relief from all material contamination. Therefore it is the recommendation of Caitanya Mahaprabhu that one should simply hear from authorities who are actually devotees of the Lord.

(N.O.D. Chapter 10)