Darn it, just noticed this was a resurrected 10 year old post, Rats I thought my answer was pretty spot on too
If the hiss and hum are coming from Pedals or the guitathen the NS-2 can help you. If it's coming from just the pedals when running on outlet power then possibly a cleaner power supply like the voodoo labs one with each power outlet isolated could help too if its a noisy distortion pedal or such like.
If the hiss is comming from the Amp/Cab post pedals or with no pedals or guitar even plugged in then I don't know if the NS-2 is going to help you. If this is the case then you maybe have to look at the amp settings and then consider if you have a ground loop with the amp or cab and deal with that