I don't have your model, but on mine: Go to MENU, click on PLUG N PLAY, click on GENERAL, click on MELODY. Chose your level including OFF. Hope this helps.
I just bought samsung LN55C610 and LN46C610 LCD TV. I am very happy with both TV picture quality, sound and features. But I didn't like start up/shut down volume. Is there any way I can turn OFF this feature. Because of that i will return TV and buy other brand.