Madhya TEXTS 17.48-49
keha yadi tāṅra mukhe śune kṛṣṇa-nāma
tāṅra mukhe āna śune tāṅra mukhe āna
sabe ‘kṛṣṇa’ ‘hari’ bali’ nāce, kānde, hāse
paramparāya ‘vaiṣṇava’ ha-ila sarva deśe
TRANSLATION–When someone heard the chanting of the holy name from the mouth of Śrī Caitanya Mahāprabhu, and someone else heard this chanting from that second person, and someone again heard this chanting from the third person, everyone in all countries became a Vaiṣṇava through such disciplic succession. Thus everyone chanted the holy name of Kṛṣṇa and Hari, and they danced, cried and smiled.
The transcendental power or potency of the Hare Kṛṣṇa mahā-mantra is herein explained. First, the holy name is vibrated by Śrī Caitanya Mahāprabhu. When someone hears from Him directly, he is purified. When another person hears from that person, he also is purified. In this way the purification process is advanced among pure devotees. Śrī Caitanya Mahāprabhu is the Supreme Personality of Godhead, and no one can claim His potency. Nonetheless, if one is a pure devotee, hundreds and thousands of men can be purified by his vibration. This potency is within every living being, provided he chants the Hare Kṛṣṇa mahā-mantra offenselessly and without material motives. When a pure devotee chants offenselessly, another person will become a Vaiṣṇava, and from him another Vaiṣṇava will emerge. This is the paramparā system.
SB 2.9.8 purport–
Lord Brahmā heard the occult sound tapa, but he did not see the person who vibrated the sound. And still he accepted the instruction as beneficial for him, and therefore he engaged himself in meditation for one thousand celestial years. One celestial year is equal to 6 x 30 x 12 x 1000 of our years. His acceptance of the sound was due to his pure vision of the absolute nature of the Lord. And due to his correct vision, he made no distinction between the Lord and the Lord’s instruction. There is no difference between the Lord and sound vibration coming from Him, even though He is not personally present. The best way of understanding is to accept such divine instruction, and Brahmā, the prime spiritual master of everyone, is the living example of this process of receiving transcendental knowledge. The potency of transcendental sound is never minimized because the vibrator is apparently absent.
letter 2- 11- 67
I wish that each and every Branch shall keep their independent identity and cooperate keeping the Acarya in the centre. On this principle we can open any number of Branches all over the world.
Conclusion- So in the above three statements by Srila Prabhupada he nicely explains the entire principle of disciplic succession or param para. First each devotee preacher must chant Hare Krsna maha mantra without offenses and be without material motives. This means one must completely obey him as our Acarya with no deviations and no exceptions. This means all those still operating within the walls of iskcon and without. To obey Srila Prabhupada means to keep him in the center as the Acarya as he says above, which does not mean anybody else can be a guru/spiritual master/acarya within the institution he founded. You can only have ONE center to a circle. Srila Prabhupada is and will remain the founder acarya of iskcon for those who obey him. And lastly he states that even though he may not be physically present, he is still present in his instructions or sound vibrations which is never minimized because to our limited mundane senses “he appears to be absent”. So these are his teachings in a nutshell about how this Hare Krsna Movement can expand into the future. No need for further ongoing wranglings or word jugglery about some conversation tapes or letters written 40 years ago. In three short paragraphs, that all sides have read, Srila Prabhupada has given us the answer, and we must obey him.