Thanks to Sri Karthi Nagarathnam for sharing this. Great treasure!
Sri Ganesa Sarma Mama’s following Upanyasams could be downloaded from the link.
1. Deivatthin Kural Upanyasam at Bangalore volume 1 – six CDs
2. Sri Maha Periyava Sapthaham at Thane in January 2014
3. Sri Maha Periyava Sapthaham and Deivatthin Kural at Bangalore in July 2017. And you can find some songs composed and sung by Sri Ganesa Sarma in his own voice at Bangalore.