Nabani Das Baul was a "Wild Mad God Intoxicated Baul" who inspired Rabindranath Tagore in his love of Baul poetry.
Baul is really difficult to understand if you want to pigeon hole them into a category it is almost impossible, they are beyond any caste, creed, religion or category... they are Free Birds, Free thinkers. However, they always understood the shastra they are poets and philosophers, their memory contained over 5000 songs and kirtan's in both in Sanskrit and Bengali..
The people of Bengal called, Nabani Das Khyapa Baul an Avadhuta, a Tantric, a Vaishnava Baul, (Bhakti Yogi) and in fact he was all three. Vishnu, Shiva, Bramha, and of course their Shakti's Laxshmi, Kali, Sarawati, with the added juice of Buddhism, and Sufi. He was a well known Yogi, and Tantric at Tara Pith... He was a well known poet and Baul singer...there are many stories to be recorded..that haven't even been said yet..
Baul is unique in that back then they learned Sanskrit in the oral tradition of hearing and remembering this gave huge memories...
Everything is in the Baul, but the Baul is in nothing.
Baul used to be both Dual and Nonduality, I say 'used to' because Baul is almost extinct and the Bauls today are nothing like Nabani Das, 'Bauls should have huge energy, magnetic electrical shakti',... today I don't think so??
It is hard to put Baul in a box, they do not like boxes or labels, they do what they want and do not want anybody to follow them.. They are the ultimate Paradox..