You need chloramine specific carbon blocks. The standard Spectrapure blocks are not enough.
Ammonia is taken care of through the Cation DI Resin.
Dwell time is king here so if you have high pressure, dual membranes, or a booster pump the effectiveness of the cartridges will suffer. Chloramines are a real pain.
I played a lot of games trying to find a good solution and short of doing a whole house system I installed a chlorplus 20BB sized cartridge (20lb carbon block) in front of my Spectrapure RODI. This has saved me a lot of cash in the long run.
Here is a thread I put together a while back that shows what I ended up doing.
http://www.reefcentral.com/forums/showthread.php?t=2483520
I use two test kits to determine if my water is safe. I have tried several and these have worked for me.
Jungle Ammonia Test Strips from Walmart. They are cheap and react every time. I have about a half dozen test kits that didn't work. Most of them test free ammonia. You need one that measures total ammonia. These work. You can confirm the DI is removing the ammonia by testing the water after DI.
A total Chlorine test kit from Spectrapure. Relativly Cheep and works well. You confirm your prefilters are removing chloramines by testing waste water.
http://spectrapure.com/TEST-KITS-METERS/CHEMICAL-TEST-KITS/Total-Chlorine-Test-Kit-w-10-tablets
Both tests will react with tap water. If either the DI fails the ammonia test and/or the waste fails the chlorine test the water is not safe for use.
If you have already made water for the 150gal tub drain it, it is likely toxic. Chloramines remain toxic for a very long time.