Gem X
From the link Rajasaranam has given, hearing "Sumam prathi sumam" for the first time, is indeed a sugam sugam. SPB's marvellous brihas , sangathis in charanam , SJ's complimentary humming, guitar punches and a nice melody in "Sallabam" scale [ For Sallabam, remember "ra ra" of chandramukhi fame or IR's own "isai arasi" in "Thai mookambigai" film? ]. What more can I ask for?
Janaki has been used only for humming, and how! Check out the guitar flourishes and the thumping rhythm.