MINI COMPONENT SYSTEM SONY MODEL MHC-GX470, SHUT OFF OR PROTECTED BY RISING THE VOLUME AFTER 20. IT WORKS EXCELLENT WITH ORIGINAL FRONT SPEAKERS AND A LOW 100W. THE PROBLEM IS WHEN I PLACE A LARGER LOW 250W OF 4 AND 8 OMH. THE ORIGINAL SPECIFICATIONS ARE: SUB SERIOUS SPEAKER, EFFICIENT POWER OUTPUT RMS CONTINUOUS (REFERENCE) 150 W (6 OHM AT 80HZ, 10% TOTAL HARMONIC DISTORTION). TOTAL HARMONIC DISTORTION: LESS THAN 0.07% (6 OHM AT 80 HZ, 90W). I WOULD LIKE TO KNOW IF WHAT THIS IS DOING IS CORRECT OR I MUST CHECK THE EQUIPMENT.