You didn't say, SS, but are you trying to get more smoke flavor in your meat than you're getting with your charcoal-only ECB? You're using a solid chunk wood charcoal and not powder-based products like Kingsford, right? If you are and still want more smoke, you know you can add smoking wood chunks, chips and pellets on top of your coals, right? Smaller pieces will just burn instead of smoke so you'll want to get a smoker box (or pie pan, etc) to put the smaller chunks like chips and pellets into.
If even that isn't smoky enough for you, I suppose an engineered feed product like the AMNPS is the next step, but it too will burn up quick if you place it on top of burning coals. You might want to try setting a 6x9 ceramic tile between the AMNPS and the coals to insulate it thermally. Or put a brick on the side of the charcoal pan and put the amnps on top of it, way off to a side, Of course you'll lose about 1/3 the coal capacity that way (so will have to add fuel more frequently) but you can always add some small holes in your charcoal pan if the reduced fuel volume slows the burn rate and temperature.
I don't put much faith in putting the amnps UNDER the charcoal unless you get another charcoal pan to put the AMNPS into and raise everything up. Otherwise, most of the smoke will probably just go radially out the side instead of wicking up into the smoker. But it never hurts to try. I think to get it to work, you'll be sacrificing quite a bit of usable vertical height in the ECB. So I'd recommend putting added smoke on TOP of the coals instead.
I also have some experience putting additional smoke generators OUTSIDE the ecb and piping in the added smoke. A $50 masterbuilt side smoker (model 20070112) is probably your most direct route to try that approach.
But the first thing I'd do is use better charcoal and real smoking wood chunks of hickory, cherry, etc!