The 40A really are very good. I don't doubt that the 50ASL are better, as they should be for the price difference. It's the only part of my system I would consider upgrading now as I am very happy with it.I've thought abot SCM40A as well since I'm sure they're cracking speakers as well, but I know I'd end up wanting the 50s in the end due to their all drivers SL specced (with 40s having no SL specced drivers). I want to make my final step and be done with it, which isn't a problem in the situation that I am in, since i really love the sound of my system. Just more of the same with as much neutrality, transparency and dynamics is what I'd like.