ok forget soundbars and all the other bits and pieces that may or may not exist, just get a lead that has the three av plugs at each end, red, yellow and white, cheap as chips on ebay, the box will work just fine, - i had a box where the scart socket packed in, I got another few years out of it using av leads - it's still going.
you won't get Hd channels using av leads but i doubt this will be much of an issue
you won't get Hd channels using av leads but i doubt this will be much of an issue