I use a simple NS-2 at the end of my effects chain, at the input stage of my amp. This is mainly to help control feedback as our stage volume is pretty high, and we're usually standing right on top of our cabs on the world's tiniest stages.

I had this one custom wired into the input of my VHT by Kevin Silva at Uncle Albert's. He wired it in such a way that it looks like it belongs on the amp, and I could easily remove it if I wanted to, or bypass it all together.