not totally gimmick. at least the high res head phone can go above 20khz (treble a.k.a. sharp sound) until 110khz the most expensive one. reach that point ppl dont hear anymore, is feeling. lol
10r cannot satisfy me too. try the 1r or 1a

can play well without pha device.
24bit is not even call as sampling rate. is bit rate (actually is volume depth)
sony jp say high res need player + head phone combination (is real btw).
source, digital music in wave, flac, or other compressed lossless codec.
software app to decode data or bit stream external dac.
after that is no longer digital domain.
hardware side, high res recording retain (keep) more detail in treble. not boost style, is what we call natural roll off.
given this condition, ur head phone must
1. not roll off treble (sharp sound) earlier that playing song recorded.
2. not boost treble, very ugly & ear piercing discomfort.
3. response correctly to the audio signal. becos high sampling will record details in the middle of the middle-ing middle... & so on.
ear piece is moving very fast to push all the sound. it need stiff material or inforcement to prevent sound distort (pecah)
above as all i know
im eager to try sony monitoring headphones

looks like I type wrong. thx for the correction regarding of the bit rate.