EUREKA !!!
It works :)))
I'm still not exactly sure how I fixed this but I managed to get it running
by following the instructions under "method2" in the following link :
http://gamunation.com/x3daudio1_7-dll-missing-error-fix-windows-78skyrim/
What little I understood is this : even though I'm on a 64bit OS for some bizarre reason I needed to download the 32bit .dll version instead of the 64bit version. (my error message didn't say the file was missing / couldn't be found, it just said that it was "unsuitable" for windows )
I installed the 32bit.dll into dayz folder, windows/system32 AND windows/wow64 folder.
Rebooted my PC and started dayz for the first time in approx 72 hours.
(just in time , I was starting to experience severe withdrawal symptoms )
JStewart , my first kill in 0.58 will be dedicated to you !
I'm off, thx for your time dude !