In professional installations every attempt is made to address acoustic issues before the room is finished. Sadly in domestic situations the reverse is generally true. As far as turntables are concerned if you have a suspended floor then a wall shelve may provide better accouctic isolation. Enclosing the turntable inside some other acoustically treated structure will also help. The undulations in a vinyl groove can be smaller than a wavelength of light and the cartridge can act as a microphone so the louder the speakers the greater the feedback and the more coloured the reproduction becomes. If you doubt this try moving your turntable to separate room, you might be surprised how the sound quality changes.