I have some old speakers in the house that I wanted to test. So instead of messing with the real stereo unit from the 80s, I bought a $30 stereo from Amazon, and new speaker wire.
The speakers sound okay, but there’s a hum coming from them all the time. Even with the stereo volume knob turned all the way down. Is this normal for stereo systems and I just haven’t noticed?
Part of the reason Amazon works well is because they sell high volumes of each product, allowing them to distribute products ahead of time across warehouses to match expected demand. You can’t do that if you only have exactly one of each item.