Ive had a hifonics brutus 1800d for a while. I have a four channel amp hooked up as well, when I had both amps hooked up I got ground noise. Then they told me the amp was bad and it would probably need replacing so I took it to a repair shop where they benched it and found nothing wrong. They also told me that the sub I have it hooked up to has a blown voicecoil. My question is, is it possible that the sub was the root of my problem? I have 4ga ground wire for the sub amp, and it was grounded to the same place as the 4 channel. Would giving it its own ground spot or getting bigger guage ground wire solve my problem?