Ok, as a business person myself I can think of only 1 reason for the "Retiring" of the CAB1600.1 and that is a high failure rate which equals to above expected warranty costs for CAB. It's the only reason you kill off a successful model and the core of your entire business. The 2000.1 isn't an "Upgrade" to the 1600.1, it's a whole new model that has been on the market and even discontinued by Soundstream (Assuming the 6000D is designed like the 5000D I Tested). I wouldn't get all excited over this one... If your looking for a .5 stable budget amp I think the best value for .5 is the PPI Black Ice 7000.1D.