How loud is a 100 watt amplifier?

Could you please elaborate on the loudness level of a 100-watt amplifier? I'm curious to know if it's suitable for a small living room or would it be too overwhelming? Also, how does its loudness compare to other common household electronics, like a television or a stereo system? I'm interested in understanding the technicalities behind the sound output and whether there are any factors that could affect its volume, such as the type of speakers it's connected to.