i have had my system in my car for about a year now. about 3 weeks ago it started acting funny, the sub cuts out when i put the radio volume above 40 now 30. im using the stock head unit. i used a meter and checked power at the amp while its happening and thats fine , power from my switch is good also. the only place where i see something strange is at my rca converter( i have one from best buy its wired off my rear speakers) when the sub cuts out i lose voltage going into the converter. did some issue devlope in the hu from playing loud all the time? i though it might me a loose connection but it will happen even when parked, i've also tried the " wiggle test" (an automotive wiring check) and nothing. i am getting a new hu and a cap in the future will this solve my problem? any help or thing to tryis greatly welcome.

no one out there is a mobile audio installer?? or anything like that?, help please!