Do they sound good at low level? If so i would suspect the drivers may be a bit smoked.Some drivers will still work after being overheated but exhibit a lowered impedance to the driving amp and do all sorts of bad things including possibly burning up the driving amp.If they are still under warranty,bring them back and tell them they better check them out again cause your 12 year old cousin can tell they are in distress and if they still can't find anyhting wrong maybe you can get him a job.But seriously,give them the smell test.Put your schnozz near the center of the woofer cone, then tweeter center to see if you detect any burnt smell at all.even a little bit can be a clue that there is a big prob.Next step is to remove the suspect from the case and give it a feel.while you are doing this,give the amp circuitry a quick visual for anything burnt or obviously dammaged.The smell test is really good for the amps as they get REALLY smelly when they are in trouble.Try to gently move the cone inward and then outward.NOT hard enough to damage it but what you are looking for is any slight drag or uneven cone movement like a slight scraping.If you have another decent speaker that is similar in size(not really necessary) and quality(i consider this very necessary),try the substitute to see if you are on the right track.What we are trying to do is narrow the prob down to the actives(amp/crossover circuitry) or passive(actual speaker mechanisms).Actives need a tech.Passives need you to get a replacement speaker and install it yourself.may be just a woof or maybe a woof and a tweet or whatever.remember,you need to listen closely(this is a mental process) to decide if what you hear(physical process) is good audio.Take it from there Sparky!This process is good for any active speaker.