Reading Bhagavad Gita is hearing from Krishna directly

This is the way of the parampara system. If we follow the acaryas, we attain the same benefit as our predecessors. If one follows the decisions of Arjuna, he should be considered to be directly hearing Bhagavad-gita from the Supreme Personality of Godhead. There is no difference between hearing Bhagavad-gita directly from the Supreme Lord and following a personality like Arjuna, who formerly heard Bhagavad-gita directly from the Lord. Sometimes foolish people argue that since Krsna is not present at the moment, one cannot take direct instructions from Him. Such foolish people do not know that there is no difference between directly hearing Bhagavad-gita and reading it, as long as one accepts Bhagavad-gita as it is, spoken by the Lord. However, if one wants to understand Bhagavad-gita by his imperfect interpretations, one cannot possibly understand the mysteries of Bhagavad-gita, even though one may be a great scholar according to mundane estimation.

(Srimad Bhagavatam  4.30.10)

Hearing from a Pure Devotee

SRIMAD-BHAGAVATAM 4.20.25
sa uttamasloka mahan-mukha-cyuto
bhavat-padambhoja-sudha kananilah
smrtim punar vismrta-tattva-vartmanah...
kuyoginam no vitaraty alam varaih

TRANSLATION
"My dear Lord, You are glorified by the selected verses uttered by great personalities. Such glorification of Your lotus feet is just like saffron particles. When the transcendental vibration from the mouths of great devotees carries the aroma of the saffron dust of Your lotus feet, the forgetful living entity gradually remembers his eternal relationship with You. Devotees thus gradually come to the right conclusion about the value of life. My dear Lord, I therefore do not need any other benediction but the opportunity to hear from the mouth of Your pure devotee."

PURPORT by Srila Prabhupada:
It is explained in the previous verse that one has to hear glorification of the Lord from the mouth of a pure devotee. This is further explained here. The transcendental vibration from the mouth of a pure devotee is so powerful that it can revive the living entity's memory of his eternal relationship with the Supreme Personality of Godhead. In our material existence, under the influence of illusory maya, we have almost forgotten our eternal relationship with the Lord, exactly like a man sleeping very deeply who forgets his duties. In the Vedas it is said that every one of us is sleeping under the influence of maya. We must get up from this slumber and engage in the right service, for thus we can properly utilize the facility of this human form of life. As expressed in a song by Thakura Bhaktivinoda, Lord Caitanya says, jiva jaga, jiva jaga. The Lord asks every sleeping living entity to get up and engage in devotional service so that his mission in this human form of life may be fulfilled. This awakening voice comes through the mouth of a pure devotee.
A pure devotee always engages in the service of the Lord, taking shelter of His lotus feet, and therefore he has a direct connection with the saffron mercy-particles that are strewn over the lotus feet of the Lord. Although when a pure devotee speaks the articulation of his voice may resemble the sound of this material sky, the voice is spiritually very powerful because it touches the particles of saffron dust on the lotus feet of the Lord. As soon as a sleeping living entity hears the powerful voice emanating from the mouth of a pure devotee, he immediately remembers his eternal relationship with the Lord, although up until that moment he had forgotten everything.
For a conditioned soul, therefore, it is very important to hear from the mouth of a pure devotee, who is fully surrendered to the lotus feet of the Lord without any material desire, speculative knowledge or contamination of the modes of material nature. Every one of us is kuyoga because we have engaged in the service of this material world, forgetting our eternal relationship with the Lord as His eternal loving servants. It is our duty to rise from the kuyoga platform to become suyogis, perfect mystics. 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.