I'm not a fan of soundbars, so other posters may balance out my rather prejudiced view of them. I think they're mostly dreadful things apart from the very best ones which for the money, you could buy a half-decent amp and set of speakers for. They're bought primarily for their looks, which is funny because I thought they were supposed to make the sound better. Rant ends.
Anyway, onto your question. It's a great idea to use your system with the TV. No it won't damage the speakers and the majority of the time it'll sound far better than a soundbar as most TV content is still in stereo anyway.
But to do so, you'll need a DAC. My own TV has an analogue RCA output which I used to connect directly to my stereo amp which worked very well, but most TV's these days only have an optical digital output. So you'll need some way of converting this digital signal to an analogue one that your amplifier can understand. DACs vary quite a lot in price and functionality, so set a budget and decide what you want it to do.
The other thing you might need to bear in mind are the settings on your TV. You'll probably need to ensure it downmixes any multi-channel signals (from TV programmes that are encoded this way) to stereo PCM signals. Or you might set your sources to do this. So if you have a Bluray player, get it to downconvert to stereo PCM.
Of course, buying a DAC opens up the possibility of connecting other digital sources to your amp too, like a computer. Some DACs even include Bluetooth or Apple Airplay which would enable you to stream music from Spotify and the like from your phone to your amp.