Summary: I use 6 of these along with two powered subs every week for around 14 hrs/week. I have replaced three circuit boards because of overload. It costs around 100-150$ to replace the board with higher end components. There are several places that you can send them to for the repair or you can buy the board and do it yourself if your techie that way. It is the most common problem with these speakers. While it can be a pain sometimes they are still worth the money.
Excerpt: First few gigs, they did really well. The sound was good, the weight was nice for hauling. Sooner or later, you WILL blow a woofer. I never managed to get above 1/2 volume on the main of my Numark NS6 and have lost 1 of 2 already. WARNING! Mackie does NOT warranty them if you blow a driver. You WILL have to pay to replace the driver, and expect $ or there about. Needless to say, mine were picked up un-repaired.
Pros: Clear Sound, Compact, Easy To Use, Lightweight
Excerpt: I just bought my mackie thump 15a at B&H. The speaker's design is modern and the material appears to be solid and of very good quality. I mounted the speaker on a stand bought at the same place, plugged the speaker on a pdj480um mixer, turned off the speaker's EQ. Driven by the mixer's EQ alone, the speaker sounds incredibly good, both on low and high frequencies.