If you are presently connected using HDMI then you do have 5.1 to the TV set, and most TV's manufactured since 2011 do have the capability of passing 5.1 audio from the HDMI inputs to the ARC HDMI that is designed to connect Audio amplifiers to it. The 5.1 audio can also use the optical output connection if the HDMI ARC (audio return channel) isn't an option available.
Previous to 2011 the only TRUE way of getting 5.1 sound....you had to connect the optical output on each device directly to the amp because running it to the TV set could result in 5.1 sound being converted to stereo. The reason was the HDMI audio inputs on the TV set could only send out Stereo Audio because of licensing restrictions.
That's why a lot of my customers have Dolby 5.1 but wonder why they only get stereo to their amps.
Direct connections are sometimes required to preserve the 5.1 surround signal.
Sky, DVD and the PS3 would likely have 5.1. The Xbox is 50/50 depending on model/year and the Wii is stereo only. You have to have either HDMI or optical output connections to get Dolby.
On my 2006 model, I have to run all my audio directly into the amp for Dolby surround.
On 2008 models like yours...it probably passes all HDMI audio directly over to the optical output preserving the Dolby 5.1 encoding.
You stated --
when we watch DVDs its is played through our 5.1 surround wired speakers and to listen to Sky or TV in 5.1 surround the DVD player has to be on
That sounds like your set up is a Combo DVD/Home theater amp with one additional optical input jack on it.
That would be the only way for both your TV and SKY channels to activate the surround sound speakers from 3 different sources (dvd, sky & TV channels)
If that's what you actually are experiencing and can attest to it functioning....then your Xbox's HDMI connection should also produce surround too. IF it was manufactured to deliver surround from any Blu Ray Disks or any Games designed with Surround sound programming that is.
And in that case....The only thing you would need to upgrade to is any present day wireless speaker combo Home Theater unit that you like. And yes, Samsung does make them. It's not important what I like....it's important what YOU LIKE. After all, I don't have to live with the decision for the next 10 - 20 years. So it's important what you like.
Samsung makes some awesome wireless units. I like them but only to the point that the bluetooth connection stays connected. When you lose the connection, and resetting it doesn't work, then it gets expensive. I'm still OLD school...I prefer hard wire that I can easily hide in most rooms.
That's why what YOU LIKE is more important than what I LIKE.
So....you know you get surround sound from all your HDMI connected units on your TV set.
You know you get Surround from all of them to your Audio amp right?
All you need to upgrade and preserve your surround sound is to maintain that TV to Audio amp connection.
Whether you upgrade your amp or you just add a set of wireless speakers to your amp , it's going to function exactly as it did before.
But don't ask me to select the brand and model of wireless speakers for you. You'd end up with a Denon 80 - 120 watt amp, a set of Boston or Boses and a wiring plan to hide it at the top or bottom of the floor, maybe in the walls if you own the home.
Wireless to me limits the Wattage of the speakers and the choices available.