Yes, I've checked that (something else which I mentioned in the OP), nothing was marked read only.
I'm betting that it was something I was doing wrong,
but since I had done everything that had been suggested that I do (as well as a bunch of other things that didn't pan out), and I keep hearing the same suggestions despite me saying that I had tried them (and in the case of the 'change the IRQ settings' suggestion, the options I was given within the program for some reason did not include said settings), I have no clue what I could be doing wrong.
Additionally I'd suggest that anyone else having problems getting sound to work from their download of
Master of Orion here, just search for another download elsewhere (the one I'm talking about is on someone's little MoO fan page), and download the version that is formatted as though it were the original disks. Simply unzip all the files from inside the disk folders and mount the directory you unzipped them to as a floppy drive in DOSBox and install the game (and subsequently get sound along with it) will be a snap. Granted you'll have to deal with the copy protection, but I think if you're savvy enough to do all that you can just as easily find the manual, or a copy protection cheat sheet,
somewhere (I just dug up my own copy of the manual I had lying around, mmm nothing beats that dusty old game manual smell
).