You can use a stereo receiver. If it a good older one with really good front speakers it will sound good. If you want to use a sub then you need one of those good oldies that have access to the preouts and amp ins via jumpers at the back. The one thing you will need is a DAC, as TVs no longer have analog audio out. This will require a DAC that converts the TOSLINK digital audio out to analog audio out via RCA cables.
If you are going to go this route, then I strongly suggest buying
this DAC from Maplin stores in the UK. They have one made for them which is absolutely the best. You can use it here as it is USB powered. It can be powered from the USB port of the TV or any USB power supply.
The nice thing about this unit, is that in addition to being very stable and not sending loud noises though your system when you shut the TV down, it has a gain control. This latter is essential otherwise the signal if often too low from most DACs. This allows you to set the gain to match other sources and the radio in your receiver.
This is a very well thought out device and much better than any similar device I have encountered before.
In the end you might find it all too much trouble and go the receiver route.
One of my three systems does not use a AV pre/pro that the other two do, but really nice vintage gear. It uses separates, so it is easy to integrate subs. It sounds marvelous. You do need a little moxy to do this well. I find most people who do this do not generally get a nice result.
Buying and AVR is easy, but not necessary for two channel TV viewing.
The radio is a Quad FM 4, the pre amp A Quad 34, the power amp to the main speakers is a Quad 909 and the power amp to the subs a Quad 405-2.
So it can be done.