On my wish list of stuff to buy is the CMC6. I've used them a few times and have had good luck with them. However, I have a friend who is selling a set of CMC5 and I was curious if the difference between the two is worth holding out for the CMC6? I am actually only worried that the roll off frequency of the CMC5 is 30Hz whereas the CMC6 is "flat" to 20Hz. Any advice?