Surely you will tell me that there are plenty of resources on the web with his concerts and that would be perfectly true. I go back to my goal of getting all my recordings on to the cloud (preferably in my own space which I can control), open it up for anyone who wanders to this site and hope they enjoy the recordings.
With so much having been reported about him, It is pointless to say anything about GNB and I will leave it that.
Click here to go to the recordings
Shankar Krish's Blog 
I was not fortunate to attend his live concerts but have listened and I have a sizable collection of his concerts. His eldest son late GBD Duraiswamy was a good friend of mine and once he presented me a book of Sri Muthuswamy Dikshithar’s krithis which is from GNB’s collection.
I have not heard him live either, but my mother has heard him a few times in Tiruchi. His concerts on the radio was primarily my exposure to his music and it was only in the 80’s that I managed to get some recordings of him.
I have heard about GBD who supposedly had a large collection of concerts of GNB as well as others.
The concert starting with Sadhinchane (11th upload) – GNB-Lalgudi-Palghat Raghu
the player stops automatically when the Bhairavi Keerthana (upachara mulanu) is being played.
The same thing happens when we play after downloading the entire concert.
This concert is not available from any other source.
It may be required to reupload the entire concert file.
K Nagarajan