Heat is the enemy of electronics, including all of that audio gear crammed into your cadenza. Over time it can cook it relentlessly. In the early days of electronic entertainment, vacuum tubes (or as our Brit friends call them, valves) were the thing—the only thing. As one of my teachers once explained, the key to vacuum tubes was the little man with a switch inside. But he must have been sweaty, as a tube device could serve well as a space heater.
Back in the day our electronic entertainment consisted of little more than a radio. The family gave no thought to what was inside until one of the tubes failed, prompting a visit to the local drug store with its tube tester and ready supply of replacements.
Then came hi-fi and an interesting thing happened. Because of the heat issue, relegated largely to the output stages of an amplifier, separates were born. The separate preamp driving an amp on a separate chassis was a popular way to go.
The divide, between separates and the integrated amplifier (or perhaps AVR), still exists today in both the 2-channel and home theater worlds. Long forgotten is its genesis, since with solid state electronics heat is no longer an issue.
Or is it?...