I bought my MM651 speakers legally off of EBay. Now that I got about 4-5 rides in before they blew, Polk says they will not replace them because I bought them off of EBay. If you do not buy their products from one of their authorized dealers, you are SOL. These speakers literally lasted me a week.
I bought a few Polk DB651's but from Amazon. Amazon will not take the speakers back because they're considered hazardous but they'll refund your credit card. At least they did for me for the 3 blown sets of DB651's and 1 set of DB691.
Well I bought the speakers in February but I just finished my custom build 2 weeks ago. They will only warranty their sale for 30 days after date of purchase.
By my guestimation, after reading forums such as this one and a couple others. Approx. 7 out of 10 people who used the MM651s have had problems. The ones that haven't love them. Your one of the lucky ones.
If your lucky enough to get a good pair their sound is tough to beat for the price. It's too bad they can't get their quality control lined out. Have heard several other higher dollar set ups and still prefer their sound. Would be interesting to know if the same troubles are being seen in the marine applications ?
I bought the DXI 6501 from best buy.....I go through about 2 pair a year but I bought the extended warranty so I just take them back and get a new pair. So the only thing I am out is the time and gas money to take them back but I wish the quality was there.