I've heard studio noise floor is typically about 15-20 dB(A), and typical quiet living room is usually more than 30 dB(A). In my previous appartement in the cit

I've heard studio noise floor is typically about 15-20 dB(A), and typical quiet living room is usually more than 30 dB(A). In my previous appartement in the city I measured something in range of 45-50 dB, which was actually pretty high and surprising to me - and funny, I didn't hear that noise live until recording and hearing back. Dithering gives about 120 dB of useful dynamic range, so I can't imagine a case where someone wanted more. You can't go much lower than the noise floor of the environment and you don't want to go too far above 100 dB, because this already isn't pleasant (nor good for your ears; 85 dB is considered the upper safe SPL limit for longer exposure). I'd risk stating that even without dithering, the default 96 bit depth is good enough in typical listening conditions.