Sometimes, we miss profound changes around us because they happen just slowly enough for us not to fully see them. It’s only when you realise that trying to perform day to day tasks without the internet is almost impossible or arranging an event with someone who doesn’t have a mobile phone is a logistical nightmare, you become aware how much things are changing in the background. When you suddenly pay attention to something again, you realise it looks very different to how you remember it.
Two channel audio is another area where this applies. In the last few years, almost everything that was a given has been tipped on its head just slowly enough that we haven’t really noticed it. For almost the entire life of high-quality hi-fi, what separated it from lesser quality hardware was that it was literally separate. It divided into separate boxes that had very defined roles: the source (turntable, CD etc), amplifier (which may be split into pre and power boxes) and speakers. If you wanted an extra function, you added another box.