Sri Krishna Vasanta Panchami
Sri Saraswati Puja

Appearance of
Sri Vishnupriya Devi
Srila Pundarik Vidyanidhi
Srila Raghunath das Goswami
and Srila Raghunandana Thakur

Disappearance of
Srila Viswanath Chakravarti Thakur
Tridandi Swami Srimad Bhakti Viveka Bharati Maharaj
and Tridandi Swami Srimad Bhakti Svarupa Parvat Maharaj

Selected reference to this day, on the Math's websites.

Audio: Sri Krishna Vasanta Panchami, 1984. Informal discourse on this special day of Sri Saraswati Puja and the appearance day of Vishnu Priya Devi, Pundarik Vidyanidhi, Srila Raghunandana Thakur and Srila Raghunath Das Goswami, and the disappearance day of Srila Viswanath Chakravarti Thakur, Srimad B.V. Bharati Maharaj and Srimad B.S. Parvat Maharaj.
Srila Bhakti Raksak Sridhar Dev-Goswami Maharaj speaks extensively about all the above personalities, 7 February 1984:
Part A, 36+ minutes, 8.5 MB mp3 audio
Part B, 40+ minutes, 9.3 MB mp3 audio

From Sermons of the Guardian of Devotion, Vol. II, by Srila Bhakti Raksak Sridhar Dev-Goswami Maharaj in relation to this day:

Chapter Seven: A Holy Day
(Web page prepared by Damayanti Devi Dasi)

Audio: Very auspicious day (1982). Srila Sridhar Maharaj chants the glories of personalities connected with Sri Krishna Vasanta Panchami. "Vishnupriya Devi's life is that of helping the fallen to go to the utmost, the highest domain of love where Krishna, Love Divine, is; where the jiva can be very, very near to Krishna. Mercy is over justice. Love is also over justice."
Srila Sridhar Maharaj's informal darshan, 30 January 1982:
(67+ minutes, 15.5 MB mp3 audio)

Audio: Vasanta Panchami, 2003. Srila B.S. Govinda Maharaj tells that this is the day of Krishna's vasanta Rasa Dance as well as the day of appearance and disappearance of several great Vaishnavas. It is Saraswati's puja day and Vishnu Priya Devi's auspicious appearance day. About Mahaprabhu's shakti, Vishnu Priya Devi, Srila Gurudev tells how she would not leave Mahaprabhu's house after His disappearance and would be chanting the Holy Name of Krishna one by one counting with rice grains and with the amount of rice chanted she would prepare bhoga to offer to Mahaprabhu. Gurudev tells that her service was very quiet but important and unique.
Excerpt from an informal discourse by Srila Bhakti Sundar Govinda Dev-Goswami Maharaj on Vasanta Panchami day, 5 February 2003:
43+ minutes, 10 MB mp3 audio

Audio: Sri Vasanta Panchami, 2011. Srila Bhakti Sudhir Goswami Maharaj explains how Srila Guru Maharaj refers to a verse of Srila Visvanath Chakravarti Thakur and applies it saying that Nimai Pandit on the eve of his sannyas had to give up the throne of love and affection that is the heart of Vishnu Priya... The Lord is the property of His devotees and principally of His sakti. What she possessed, she is willing to give that up (when Nimai Pandit left to take sannyas) so everyone else could be beyond liberated, that they can have that.
Informal discourse by Srila Bhakti Sudhir Goswami Maharaj on 8 February 2011:
53+ minutes, 9 MB mp3 audio