So your saying nothing less than a full 188 db dynamic range can do real sounds justice. I though it was actually a bit below 0 db SPL. Just rounding off we need 200 db dynamic range. Then again, the masking that occurs (perhaps permanently) with 194 dbSPL would be extensive.
No, I'm hardly saying that. Useful sensation happens from about -10dB SPL to about 90dB SPL then the mechanisms start to choke.
At 140dB you risk instant hearing loss.
194dB would destroy your middle ear in one pulse. Also your house, your trees, your car, your land, your body. The point is simple, the only transducers that hit 194dB are military, and to be kept "far away from us".
As to noise floor, the 6dB Noise floor amounts to something like -18dB SPL or so in the erb you are most sensitive in. The actual noise is roughly white, 20-20K broadband noise, but most of it is in frequencies where your ear is not so sensitive. Curiously, that level is *JUST* below the absolute threshold of hearing. A very few people have reported, in the AT&T anechoic chamber (which used to be very, very quiet inside, but which was at last experience, rather neglected) maybe hearing this. Young people, sitting quietly. When you sit there quietly you easily hear your heartbeat, your breathing, blood flow in the head, etc.
Using a good, high quality audio system, I can see up to about 18 bits being necessary if you have an absolutely quiet listening room, which is kind of rare in this day and age.