I haven't auditioned the MA6 or any cables in the 5 & 6 line. I have level 4s all around. Unlike Tvad, the difference between the 3 & 4 levels was quite pronounced. Considering levels 1-4 I prefer the 4s. Sometime I will get around to trying out the 6s, but it took a long time to properly get the 4s settled into my system. I really like them. If you are wondering where to start (and perhaps end up), I'd recommend the 4s, but be prepared for a long break in (even when you use Mike's breakin service) and settling in process. I'd seriously estimate hundreds of hours, but the wait is worth it. These cables not only solved many problems with one system, they also brought a very rewarding musicality to my systems. Mike Morrow is a great guy to work with. I'd discuss any and all of your thoughts and concerns with him when you choose to make your selection and purchase.
Ed
Ed