My sub has a constant hum even when it is not hooked up to anything except being plugged into the wall. I tried using a cheater plug, plugging into different outlets, different houses. I'm thinking the amp might be bad. Problem is that this is a DIY Tempest sub i bought 3 or 4 years ago and I can't remember the guys name lol. I know its not under warranty but i'm hoping he could help me fix it. His name is Darren I believe and lives in Washington State. I am pretty sure its a Parts express amp. Would it be possible to order one and replace it myself? Any help on this issue would be appreciated. Thanks.