Maybe I should explain a bit more where I am coming from. Right now I sort of separate my hi fi playing from my bit reduced playing. Hi Fi involves a FIIO X3 or X1.
I also have a Tarkan modified ipod 5.5g which can play FLAC redbook files using Rockbox and ALAC files using native IOS firmware.
Bit reduced playback involves an iphone 6, and I can also playback non-bit reduced files using ALAC or FLAC with some apps. Sometimes I hook up my E07 Andes to that, but that involves carrying a second piece of equipment and the E07 can't handle 192khz.
So I was thinking that perhaps I could come up with a file format that utilizes the maximum native resolution of the 5.5g and iphone 6, and use that more often since I do not want to carry around too much equipment day to day.
One thing that still confuses me is whether the iphone 6 and the ipod 5.5 g can natively handle 24bit playback. There was a pretty good analysis that I recently saw that said that although the chipset can handle that, the units are still limited by software to 16 bit. I know Rockbox can down scale bit rates, but I am still not sure exactly what the native limits are with Rockbox and 5.5g.
So if 24 bit 48 khz is the top limit of the idevices, then I might create some files for that. I don't want to use ALAC, in part because I really do not like itunes and prefer to work with Rockbox and FLAC files are something of a standard and ALAC is less so.