My living room isn't big. It's a small living room, even by Norwegian standards. It measures approx. 3,6 x 7,1 meters (11,7 x 23,3 feet), but I'm able to use half of it for my hobby. (I've got a tolerant wife)
My room measures pretty well to be a normal living room. I've got a frequency response of plus/minus 4,5 dB from 20-16.000 hz. Over 16k it starts to roll of smoothly.
The electronics are stacked inside cupboards from IKEA, but the amplifier and multiplayer sits in a rack from american manufacturer Audiophile Vibration Control. I use their isolation blocks under all my equipment, too.
Power isolation is Isotek GII Sigmas for my source components, and Isotek GII Titan for my amplifier. The combined diffusor/absorbents on the wall just over my bench, are from Vicoustic. There's also a ultra sound vinyl cleaner (with vacuum dryer) from JAS. Signal cables from Vovox and Blue Jeans Cable, speaker cables from Blue Jeans Cable and power cables from Isotek and LessLoss.