Definitely not an SD card. As far as I know, there has to be a slot in the laptop to add a sound card. I've never added components to a laptop, so I don't know any more than that, and I don't know if some or any of the Asus laptops have an available slot.

Of course, the on-board sound available now may be better.

I've always had premium sound cards in my desktops, so my expectations may be high. In a game, the Asus sound is fine as I always have any music turned off. I would not listen to music on the laptop, except for brief moments. Tinny, tinny, tinny.

Writing this makes me think I need to get on the stick and fix my desktops. :)

Wessex