Hey everyone I am new and if someone can help please do. I have an older polk sub that suddenly makes humming noise even when disconnected from amp.The problem is it will cost me 75 dollors just for dealer to look at it. I am wondering should I take money and just buy new one. my budget is around 250 to 300.The polk I have now is a 12 inch bottom fireing. My room is very small. Thank yo for any ideas.