OK here is the setup, I just decided enough is enough and put a sound system in my STi. I went with an alpine IVA-900 head unit, diamond audio speakers (with crossovers) in all 4 doors and an eclipse amp. All was installed by a professional installer at his shop. Now here is the issue, after about 10 days with the system out of nowhere I got this terrible sound coming from the speakers, the best way to describe it was a scratching/sucking/popping sound at VERY high volume. it happened regardless of what the headunit was doing at the time, and was repeatable. I brought my car back to the installer who installed my setup who tested and it was determined that it was the amp that was causing the problem. He was certain because as soon as he unplugged the front speaker wires from the amp, the problem stopped and normal sound came from the remaining 2 channels. We sent the amp back top eclipse who sent us another amp, installed it and 5 minutes later I had a similar but not nearly as intense sound coming from the speakers. does anyone here have any idea what else it could be? Thanks ahead of time for any help.