I hooked up my trusty old Logitech speakers to see if they still worked. They did, so I booted a game and sheepishly turned the volume way down in fear of annoying my neighbors, immediately remembering why I had these stuffed in a closet for almost 10 years.
Even if I lived in a soundproof house in the middle of nowhere I'd still be self-conscious enough to just use headphones instead 
I have a 50W Marshall amp with a stack speaker plugged into my computer
But I generally keep the volume "as low as possible while being able to understand what's being said", because I used to work around aircraft and I'm keenly aware that I've lost some hearing and want to protect the rest of it.