It's difficult to do anything with an all-in-one set as the design is pretty much limit any adjustment. It is designed more for ease of use than performance/sound quality. The all-in-one system is a beginning and the end by itself. Not much you can do to really improve it, less so when you think of marginal return, ie Bt vs. performance improvement.
You could try upgrade the video part. Try CANARE or Extron (I prefer CANARE for entry level picture cable but Extron may also be OK, providing the price and availability of the trial service)
However,
I would highly suggest you to try the product first before you buy as I'm not sure you'll see the difference. You could borrow from others or use a trial service. I only know
www.avbestbuy.com that offers such service.
I couldn't stress enough on 'trial before you buy', particularly on entry level system that you may or may not see the difference. My experience is that the smaller the display, the less TV got calibrate, ie using DVE or AVIA at minimum to adjust brightness, contrast, color, hue and sharpness, the more difficult you see any improvement. I once 'CANNOT' notice any difference between S-video and composite video cable on an all-in-one set (I believe it's Sony) before I adjust the TV using AVIA. It has been well known that the picture quality of the S-video and composite is world apart and S-video is the superior one. So, try before you buy, if possible.
I would say forget about the upgrade on audio part. Save your money to buy more software or upgrade your whole system are better.
