160W~ Stereo audio amplifier build, where to start?

I would like to attempt to design and build a 160W~ at least 80W per channel stereo amplifier (question below). I have never touched audio stuff so I googled first, but after some searches I haven't found many or any solid starting points. So I have some questions.

What type of components should I be using to achieve this? I've seen something called a Class D amplifier. looked up operational amplifiers on TI's site is this something I should be looking at?

The speakers I have are 80W each and I have two of them, would I need a 80W continuous amplifier to drive these? do the ohms of the speaker matter to me?

Should I build two mono amplifiers and use one for each channel?

Any general pointers to powering the amplifier(s). eg using a SMPS instead of a Linear PS or vica versa?

Apart from that first post on r/AskElectronics, I also tend to get most of my components off ebay so components easier to find on there is always a plus.