My original post still stands.
When a file is requested from the hard drive, the OS of the keyboard looks in the file table to find where the file is stored, it then moves the head to the position on the hard drive where the file is located, (Each of the samples in a sound has its own location) and then proceeds to load the file into memory, (Multiple files in the case of sound samples) now as the hard drive is mechanical, there is no way this can happen fast enough to be able to play samples direct off the hard disk in real time.
Midjay just plays the wav or mp3 the same as a CD player plays a CD, which is not classed as disc streaming.
SD 1 (Like most other keyboards) has to load the complete loop or sound into memory completely before it can be played, Gigasampler does not, as it combines the 2.
As an example the Colossus VST has a sample set consisting of 160 sounds, and would require a total memory of 32 GB to load all the sounds in, which is not currently practical, (Don’t confuse MB with GB) Disc streaming solves this problem.
As in my previous post the only 2 physical arrangers (That I know of) that can perform true disc streaming are Wersi and Lionstracs.
I hope this clarifies my previous post.

Bill