Living in California has enabled me to deepen my study into the life of Adi Shankara by coming into contact his lineage. Adi Shankara was an 8th Century bhakti philosopher. His works have been reiterated by the likes of Sathya Sai, Mata Amritanandamayi,
Lalita Sahranama: 1000 forms of the feminine divine with many references to
Soundaraya Lahari: A treatise written on Adi Shankara regarding Sri Chakra and its methods.
Amma Question and Answer:
Disciple: "What is your teaching on Sri Yantra?"
Amma: "Historically, those who made a ritual Sri Yantra out of metal also observed strict vows, like fasting, and ceilbacy, and wore wet clothes during the process. They chanted special mantras and the as a result of these practices, a special power was transfered to that yantra.
Nowadays, most people use a machine to make the Sri Yantra. Therefor, it is not imbued with the power of one made in accordance with the ancient tradition."
(Amma: Healing the Heart of the World. by Judith Cornell)
Mantra, Chakra, & Upasana. Maha Periyava discusses the meaning of Sri Chakra. He also goes into detail of mantra, chakra, and upasana. In this discourse (open saved version) he talks about the path of Sri Vidya and