Re: Speakers cut-out at high volumes
It is not the speaker nor the ground you are simply overdriving the little internal amplifier in the head unit. While rated at 4 x 35W, realistically you are only really getting about 12-18 watts RMS to those speakers. You are driving the internal amp into clipping and the square waveforms and causing the sound to cycle.
If you want it loud get an external amp, even a small one will make a tremendous difference over the deck's internal power.
1995 Oriental Blue BMW 525i 5 Speed
Stock Alpine System Actively Crossed Over & Amped w/CD 6-Disc Changer System with a/d/s 235is comps in front (3-Ways front, 2-Ways rear) sounds really good. All functions are displayed on the dash's check control display module.