With all due respect Ganges, the stock OEM HU is crappy. And that's an understatement. Music is all about clarity. Which means you should be able to clearly hear individual instruments, irrespective of the volume. Infact, the acid test is that at low volume, it should be crystal clear. Distortion at higher volumes is more a sign of weak amp and/or poor speakers. Coming to the case on hand - Linea OEM speakers are paper cone. Even if the HU is remotely decent, the speakers spoil the fun. That's why the first recommended upgrade is usually a change of speakers. Also, what you're facing is typical and expected of OEM speakers. IN due course of time, unless played at low volumes, they are bound to cave in.