i put my dd3 at the end right before my amp so i goes guitar-ns2-loop of ns2-dunlop wah and maxon od808*-end loop- ns2 output-dd3-amp best results i think also it says to do this in the manual.
plus i searched a while ago when i started to get back into anolog pedals and it said anything other than delays, overdrives, and wahs should be infront of the amp because you get a better tone outta them where as phaser, flanges, chours, acoustic sims, things to that nature should be put in the effects loop. I did it and it seems to work out amazing for me, i also found if you want to stop guitar hum from pickups infront of the amp and if you jsut want to quiet the hum from the amps channel effects loop. Im debateing to get a rack isp noise gate for my effects loop and leaving the ns2 infront for my noisey guitars lol