You can usually spot a blown driver/tweeter when something sounds funny with the bass. One way to check them is to FIRST - TURN YOUR SYSTEM DOWN!, then go around to each driver/tweeter, put your ear up close and listen for any imperfections (usually a snap crackle or pop or no sound at all).I sometimes use a couple pieces of cardboard to deflect the sound away from the driver I am checking, or cup it with my hands.
I usually use something a little bassy as source material. This seams to work pretty good as I have pin pointed two blown tweeters over the years with this method.