Panchratra is part of Agamas.
Studying Vedas, Upanishdas and Puranas and understanding them on your own is next to impossible.
Saints show the path on which true happiness is found. Greatest of saints have established Panchratras as most important of tradition.
Agamas are texts which have established importance of temples, idol-creation and chanting holy names.
Panchratras have a great influence on Hinduism along with Vedas.
Jiva Goswami had following to say about Panchratra(Taken from Wikipedia article):
Jiva Gosvami had stated in his Paramatma Sandarbha, forming part of six principal Sandarbhas, or philosophical treateses of Gaudiya Vaishnavism, that, "Seeing that the imperfect scriptures in the modes of passion and ignorance bring only a host of troubles, and also seeing that the original Vedas are very difficult to follow properly, and thus being very dissatisfied with both of these, the all-knowing scripture authors affirm the superiority of the Pancaratras, which describe the pure absolute truth, Narayana, and the worship of the Lord, which is very easy to perform." In the same Sandarbha Jiva Gosvami states that god himself, Svayam Bhagavan, had spoken the Narada Pancaratra, which is accepted as a pramana by Gaudiya scholars.
Panchratra is made of two words 'Panch' and 'Ratra'. It literally means 'Five Nights.'
Panchratra reminds you of greatest of sages and devotees, especially Narada.
Vishnu worshipers of today, represented in a wide spectrum of traditions, generally follow the system of Pancaratra worship. The concept of Nada and Nada-Brahman appear already in Sattvata Samhita or Sattvata Tantra and in Jayakhya Samhita, two texts considered most canonical of Pancaratra texts.
Omkar is primordial sound(nada) which is enchanting and emanates from the flute of shri Krishna, Alternatively it's Rudra(as suggested in the Krishnopnishada).
Madhavacharya(Anand Tirtha) established very long ago that chanting holy names of Hari is only way for deliverance in the age of Kaliyuga. In a way, he founded Gaudiya Vaishnavism, though it was Chaitanya Mahaprabhu who stressed most on chanting Hare Krishna mahamantra on the basis of Kalisantarini upanishada. Srila Prabhupada popularized it amongst westerners.
Chaitanya Mahaprabhu's teachings are in perfect alignment with Panchratra texts.
Bramha-Samhita is a most important Panchratra text.
Ramanujacharya also established supremecy of Panchratra texts.
Thus Madhvacharya, Ramanujacharya and Chaitanya Mahaprabhu, three greatest of scholars and devotees and most brilliant crown jewels amongst learned established supremecy of Panchratra texts in the age of Kali.