I have been using a Lyman Turbo tumbler for years in my apartment, and never had a complaint. Only ever used it during the day though. Placed directly on my hard wood floor the tumbler sounded like it would eventually shake the roof down. A queen sized comforter, folded into a 3 ft square was about 12 inches thick. a 2 ft square peice of 3/4 inch plywood on top of the blanket gave the tumbler something steady to hold onto so it wouldn't tip or shift around too much, which would minimize the effectiveness of the tumbler. A 1/4 thick rubber yoga mat on top of the plywood ensured maximum traction on the plywood. Running the tumbler with a full load of media, but only 50% capacity for shells cut down on alot of the clinking of the brass.
For my new method, check out sinclair internation for CRAZY CLOTHS and the lyman universal shell holder. The shell holder allows you to spin the shell with an electric drill. The cloth will remove all dirt, residue, and return the case to a ultra high shine in about 5 rotations of the case. A variable speed drill at about 200 RPMs means about 2 seconds per case. This is how I do all my rifle cases now, and it is very quiet.