It is not desire it is practicality. With cats in the house there is always some fur floating around and I feel more relaxed thinking that fur won't fall on the LP while playing. And if I am more relaxed then the sound will be better with the lid on, even if it isn't. The lid cannot uniformly 'amplify' airborne vibrations though it could resonate and exacerbate certain frequencies. Maybe the lid doesn't absorb much energy from the air and what it does goes into the plinth instead of directly to the platter/arm/cartridge. Dunno, but I won't experiment for the reason given. Also, I have panel speakers and my LP12 is placed at the dipole null so the direct acoustic feedback is probably 1/10th, or lower, than that of a normal domestic arrangement.