you're saying you can hear tweeter hiss while music is playing when you have anything under 110db sinad? (for myself, as a general rule I would work to eliminate any tweeter hiss anyway)
When talking about tweeter hiss it is more important to discuss absolute noise level at the amplifier output rather than a relative measure like SINAD or dynamic range. I am saying that I can hear tweeter hiss with a DAC with 2 x 10^(-100/20) = 20 uV residual noise when paired with a low noise (45 uV residual noise) amplifier of modest gain (25.6 dB). End result at the amplifier output is sqrt[(20 x 10^(25.6/20))^2 + 45^2] = 384 uV.
I don't know exactly where the line is between 100 dB and 110 dB at 2 V but I can say 110 dB is silent and 100 dB is not. Listening tests and measurements of various DACs discussed here in more detail -> https://www.audiosciencereview.com/...m-china-with-topping-performance.24768/page-2.
EDIT: Should add this is only during silent parts of tracks but it is annoying and definitely detracts from the experience.
Michael