Stereo issue or me being thick!

Hey guys, I have a FL2 2011 HSE had it couple of months and what an amazing car, anyway one thing that's grating my nerves is the stereo, it had the 6 cd changer unit with the amp and subwoofer but if I have the volume anywhere near loud or even just normal the sounds adjust itself dramatically, thought it was the AVC levels but that's not even on, I understand that when the bass kicks in the amp has to balance the power so the high tones get cut but this almost goes silent, I can have it up to volume 27 and its just quiet but then when you come to a traffic light it whacks up really loud and full of treble, I have searched and searched the Internet but no help at all anywhere and wondered is this me being stupid and it's a simple issue or is there a fault here Thank you

Sounds like an issue with the amplifier. Have you played with the Logic 7 settings, to see if those alter the sound issue?

The sound shouldn't change at normal or even loud volume levels. Mine is the 9 speaker system, which is very loud, especially so now I have the installed B & W mid bass speakers in the front doors.

Was the volume levels get excessive, the amplifier attenuates the lower frequencies, as those tate the most power to reproduce. This however is normal for pretty much all production car audio systems.