bobby1945, in my office we use a Water Pick with warm water and peroxide. You do have to know where you are aiming so not a good idea to try on yourself.
1+ aewarren, lights off, eyes closed. A little rope doesn't hurt either.
Speaker placement is not a tweak. It is basic system setup.
1+ secretguy, the physiologic term is accommodation.
Is acoustic management a tweak? If you are actually measuring the room I think not but I suppose the measurement microphone and program are a tweak as they are not commonly purchased. It always helps if you know what you are doing. Also, once you know what you like you can quickly achieve similar results in many if not most other rooms.
yugebohner, I would think coating your significant other in contact cleaner would be more fun.