A charcoal filter Can remove or reduce chloramine, but the flow rate must be insanely slow, and you must recirculate thru the filter. In practice it is extremely difficult for the home brewer to acheive this. Campden is SOOOO much easier, why try anything else. 1/2 tab for 10 gallons, just a little dab'll do ya.
I recently went to a .5 micron carbon filter for my water. I find that If I run it slowly and give it minute or two, the water tastes pretty good. I run it into another bucket then directly into my HLT. If I rush this, it tastes chalky. I'm thinking that might be the charcoal. The .5 micron will remove chlorine, but leave behind some good minerals. The key is to taste it and use the water only when 100% satisfied with the taste. I'm still dialing it in, but I've been very satisfied with the beer so far.