I have an MTX 81000D, powered by an Alpine CDMA 7875, pushing a 15" Kicker Solo Baric. I've had it for 2.5 years, and it's been great, no problems. Recently, however; when system is turned up halfway, and base is probably 60-70%, the subwoofer starts hitting full, and pulsating. I.e. thump thump thump, at what sounds like 100%. It doesn't stop when I turn the volume off, only when I turn the headunit off. Everything works great below this halfway volume or 60% bass. All connects and grounds are tight and clean. The amp seems to make a staticy noise (not the speakers), sort of like sparking (I'm pretty sure thats not what it is) when the amp starts pulsating. It's all still under warranty, but I was wondering if anyone had any thoughts. Thanks.