You don't have any HIFI or Home Theatre shops in kanyakumari but in Trivandrum.
There is a shop called Eham digital in mall of travancore. It has AVRs and speakers. Infact, they have a demo room with Benq 4k projector, POlk Signature speakers, oppo Bluray player and SOme Denon AVR. Polk subwoofer too. You can ask for a demo there. Also, search if there are any HT shops in Trivandrum.