Hi-Rez music is just as it is stated, Hi-Rez. Everything starts at the source, if the source is a IPhone or some other portable device 95% sure it will not be Hi-Rez. Mp3 and ITunes from downloaded sources are about 256kbps range and streaming services may be even lower in some cases. If you plan to rip your own collection the best format is .WAV if disk space is a problem/issue go with .FLAC. There are sites (HD Tracks) that sales Hi-Rez downloadable music, but it is not cheap. Even then you need to make sure whatever device you plan to use as your transport can actually playback those files.

As far as your transport option you need to be looking at either stand alone DNLA player that can support storage disk (USB, Hard drives) or a computer setup for storage/playback through a Digital Audio Receiver (DAR). DAR's are the more popular choice do to their flexibility in placement.