From your list:
The A&K Jr doesn’t have LDAC, balanced output or line output.
The iBasso DX120 doesn’t have Bluetooth at all, so no LDAC there.
The Cayin N3 doesn’t have balanced output or, as far as I can tell, LDAC.
All DAPs exhibit some noise with sensitive, low-impedance, IEMs - though it may not always be audible to a given individual with a specific IEM. And some mask it by switching off the amplifier entirely when nothing is playing. Playing a file of silence will let you determine if that’s the case, otherwise it can be hard to tell if the noise/hiss you’ll get when listening to music is from the track itself or the amplifier.