All devices that output audio have a DAC, the style although using a SD808 does not use the SD DAC but other solution that has a fixed bit depth of 16bits and a 48kHz sample rate. So no it does not support 24bit audio rendering, even if you use the Samsung trick to fool Poweramp into enabling 24bit audio output the android mixer will render the audio as 16bit 48kHz. @JJ Singh
No one is saying that you shouldn't use the high resolution output but trying to explain why a standard resolution stream has no noise and why you may have noise in standard resolution output.
The only player that I'm aware that uses direct DAC output is UAPP because it uses a custom driver to acess the DAC (either built in or USB), the rest of the players uses the android native driver.
Now if you make the player apply some specific flags to the stream, audio may be rendered via a different path or use different features of the DAC and fix some of the issues you're having (that's what Poweramp and some other players may be doing).
Regarding sample rates, Nyquist–Shannon sampling theorem says that in order to record a specific frequency you need to have a sample rate that is at least twice the frequency of the original signal. So a 48kHz sample rate will produce audio with a maximum frequency of 24kHz (this related to "sampling rate of 48KHz(~24KHz preserved)", nothing is lost, it's just the way it works).
Also, even your headphones are overkill (regarding to frequency) as the human ear tops at around 20kHz and hearing degrades with age (not volume but sensitivity to higher frequencies).
In the end I cant really put my finger on why with different devices you had noise but as @Noobie said, "Noise even at a low volume means faulty DAC" or as I've said bad audio implementation.
I've had a few devices (Motorola Defy, Samsung Galaxy SIII, Moto X Style, Umidigi Crystal, GGMM A1 DAC, S.M.S.L. iDEA USB DAC) and only the Defy had background noise.
High resolution output does not magically produce higher quality audio.