Henry Williams:  I need a portable dac/amp that can play 192/24 bit audio files.
Juan B:  Headphones will not be 192-24bit. This is a digital spec.

Juan B:  Is there anything else I can help you with today?
Henry Williams:  http://www.bhphotovideo.com/c/product/839353-REG/Fiio_E17_E17_USB_DAC_Headphone.html/mode/edu
Henry Williams:  this one says S/PDIF: Up to 24-bit/192 kHz, max . how do i connect the headphones to this so that it plays 192/24bit
Juan B:  Again headphones will not be 192-24bit. This is a digital spec.


Juan B:  Have a good day and thank you for using B & H.


 
 
So is there a portable dac/amp that I can connect my headphones to that will allow me to enjoy 192/24 bit music files?

what will you be using for a portable source?

The Fiio E17 will do 192/24 if you use SPDIF.  But what he might have been saying is that no headphones support the frequency range you would be getting at 192KHz, meaning your headphones would need to be rated to output frequencies up to 96KHz to take advantage of that sampling rate. Of course the point is kind of moot anyway since we can't hear above 20-22KHz, but I will direct you to the sound science forums if you want to know more about that.
 
http://www.head-fi.org/f/133/sound-science

The focus on 24-bit is also moot.  It's not an indication of the quality of the DAC.