Here I was thinking I'd missed something. I figured out a way to turn 16bit into 8bit samples though, so I can use everything I normally do (like stuff from freesound.org)
Thanks for the replies, been very helpful.
If you're interested here's my second .mod in years, unfinished & made with the few samples I had before I started sample hunting, but hey. Supposed to be played at 150 bpm, but I haven't yet figured out the code for song speed, so it only plays right in Protracker on my system.