So, I've rediscovered my N/S stick and while I find that I can get a really amazing "singing" tone... almost violin like... when using a high gain amp simulation like Guitar Rig, I'm getting a LOT of hum. My Steinberger guitar and bass don't suffer from this, nor does my G&L and they're all going into the same MOTU 828. Could there be something wrong with the internal grounding of my N/S? I hope this isn't a design flaw and maybe something as silly as I need to get a better stereo cable. (I'm using the one it came with)

Does the NS/Stick have a mono setting ? Just try a mono cord.

Is your NS new or used? I had a grounding issue crop up on my used NS and it ended up being a worn out output jack. Does the problem change when you switch between stereo/mono?

Also, if you haven't done this already, use that y cable with your other instruments and see if the same issue crops up.

I did try it mono with a cable I know was good and it didn't change. Switched the stick to mono, no difference. So I'm thinking it's not the cable for sure. Might be the jack. I guess I could dig into it and see if anything isn't connected.

How are you plugging in your stick to your computer interface? I always noticed a hum through anything from a guitar to a stick by just plugging it into an audio port. Check if your input has a dedicated specified guitar input (i think it has something to do with the impedance). Either that, or if you have a friend with a spare stomp box, try plugging it in through there. Believe it or not, I found that cleared the sound up immensely for me.