I am in the process of replacing a plastic shower stall with a fully tiled shower stall. Shower is in basement and is on concrete slab. After removal of old base, I realize I have a 2" steel pipe that is currently at slab height. I also note a crack in the concrete (not near drain) across the area under the shower. I was planning to use Schluter-Kerdi on tapered mortar bed-I think I have two problems. I need to transition the steel pipe to ABS or plastic well below grade and I probably should use a liner due to the crack. Any guidance will be appreciated and may help keep me in good graces with the Mrs. Is the DIX system a good liner solution or do you have any other suggestions.