I've got a couple sets of the kappa perfect 6.1's and they scream... They can take a beating, your ears will be blown before the tweeters. I didnt/dont notice as much bass response ( not that i was looking for it ) from the 6/5inch kappa woffers compared to the MBQUARTZ but i dont think ive heard the mbquartz play as clear at high vol. as the kappas. me and my buddy own both brands/models and its pretty easy to compare w/ a similar soundstage. I have baffles, and dynamat going in the doors soon so maybe that'll help