I have a 5+1 theater system(can use USB or DVD) which doesn't support MKV play.
How can I use my Mac to burn the .mkv files into high quality dvds ?
Sounds like you need Toast Titanium. Toast will take individual video files and put them into a DVD player compatible format. It doesn't have many options for the DVD's menus, but it's a quick and easy way to burn video files to DVD. It also has many supported formats.