I also use Cubase and GTR3. Even the most expensive guitar will produce noise if the gain levels are too high, crappy instrument cables, poor audio interface, etc. It turns out that my noise solution is a *free* vst plugin that comes with Reaper called "ReaFIR". I'm always wary of "free" solutions to problems, but I'm dead serious about this. I put this plug at the very end of my signal chain and it virtually eliminates *all* hiss/hum, even on high gain amp sims. I even stopped using noise gates (which I detest). Very light DSP footprint as well. You may find the other plugins ReaFIR comes with very useful, too.
https://www.reaper.fm/reaplugs/