VOSIMSynth

This looks really promising but so far I cannot use it in Windows because it doesn't show up either in Cantabile Lite or LMMS.

Thanks for the heads up. I edited the description to point out it currently works best with Reaper. I did however just test it with Cantabile Lite and LMMS. Cantabile Lite seemed to work fine (but note the downloads here are 64-bit and don't show up using 32-bit Cantabile). It showed up in LMMS but there seems to be an issue with the graphics rendering that makes it pretty much unusable. I'll add LMMS support to my issue list in the mean time.

I'm not having any luck in Savihost or Sound Bridge either. Is this Win10 only or does it have special CPU requirements? I'm trying to get it working on Win7 on an old laptop.

Ah okay, yes the build linked here is for processors with AVX2, which would definitely cause issues if your processor doesn't support that extension (pre 2013 I think). If you visit the latest AppVeyor build page, you'll find binaries for processors that support only the SSE2 extension (and also processors that support no extensions). The SSE2 build may give you better luck. Here's the direct link to the current one: https://ci.appveyor.com/api/buildjobs/t8leild6fcr4q1sx/artifacts/_build64-sse2%2FVOSIMSynth%2FRelease%2FVOSIMSynth.dll.

Sorry for the trouble, if the above doesn't solve it for you feel free to reach out directly via PM or email (austen520 at gmail), and I'd be happy to spend some more time getting this resolved.