Based on reccomendations here and elsewhere I have ordered a JBL NSP1II speaker system. Also ordered is a Dayton 10" 100w Sub and a HK AVR 225. This is my first 5.1 system and I have some questions about speaker placement and setup. The room I will be using is about 18 feet wide by 20 feet deep. My monitor, the N-Center and two front N24's will be on a half wall about 15 feet from my listening position. There is a stairwell and a full wall behind the N-Center and the front N24's. The rear N24 surrounds will be on side walls, inline with my listening position. The right rear near a corner, and the left rear on a short wall facing the right rear. There is a hallway in between my listening position and the left rear surround, so it won't be in a corner like the right one is. The right side wall of the room is solid except for windows, the left side wall has a fairly large opening to the kitchen. The best place for the Dayton sub is going to be in a corner pretty much underneath the right rear surround. My cable run for the sub is over 25 feet so I'm going to use RG-6 cable for the long part and a short piece of sub cable from the wall connections. I'm using 12ga low voltage outdoor lighting cable for the rear surrounds since my cable path to them will be around 30 feet for one and 40 feet for the other. 14ga speaker wire will be used for all the fronts. Questions are: 1. If I mount the two front N24's at or near the top of the half wall, I can keep them within a couple of feet of the N-Center vertically but they will be behind it by as much as 20-24 inches. Is this a problem? 2. I plan on mounting the rear surrounds so that their bottom is 6-6.5 feet high to make sure no one runs into the left one going down the hall. This is a bit higher than some recomendations I have seen. Is this a problem? Any other advice on this setup is appreciated. Thanks.