The soundtrack is all from the EPS factory disks, megamix style.
OmniFlop will work fine, it is what I used to image my EPS disks. The cool thing about this emulator, and disk imaging in general, is that the programs don't actually need to really understand the format, they just have to copy it and reproduce the data properly.
I read in disks to OmniFlop, created generic images, then used the HxC software to create images from 'raw' files. I am not too well versed in this, but I did need to change some settings to be able to properly reproduce the disks into an HFE image (for use on the emulator). I found the settings via the EPS thread in this forum.
Maybe I should have included this first, or should put a link to it in the YT vid, but here is the full writeup on the process:http://casavista.blogspot.com/2011/02/resurrecting-ensoniq-eps-classic.html
Keep in mind that you still have to fake the sampler out into thinking it's using 'disks', so it won't be any faster and you will still need to 'swap disks' (via a button press). However, with the S20 having such a huge memory capacity for it's pads, this might be something you just need to do once at the beginning of a performance...I don't know how you use the machine.
Also, one thing I failed to realise, is that create new disks, currently, you have to create them on the PC and drag 'blank' images into the emulator. It's not a huge deal, you just copy and paste an image of a blank, formatted disk and make sure they are on the card already. Requires a little foresight, and note-taking to remember which files are on which image.
Btw, I am using the SD card version, which I would highly recommend over any usb solution for a sampler. leave the computer at home.
ps. Totally unrelated, did you know the S20 is bendable? http://www.circuitbenders.co.uk/synthmod/S20.html