While I don't have any of these, I wonder if you have a noise suppression unit? If you do, I'd test out your options. Sometimes your guitar signal is really noisy because of various factors, or your amp puts out a lot of noise...so it would be situational I suppose.
i have an ISP Decimator on the way, i just thought i'd ask...
Because i see alot of people using it before the amp, but then when I think about it, I think wouldnt it be better in the loop, to catch noise from the preamp? anyway i dont know shit, i'll definately try it in both positions when i get it.
NS-2 infront of the amp - My Single Recto isn't noisy at all, and having the gate infront of the amp kills feedback, as well as hiss from OD pedals, guitars, etc.