A very old thread but thought another mini p180 user may stumble here... had lots of HDD noise on the front audio assembly I fixed this by simply unplugging the esata port. This is good to know since Antec Australia would not send me a replacement front panel cluster (I was willing to pay whatever it takes). They said they are unavailable even though they are in stock in the US.
Ah well hope it helps some one else.
I celebrated a bit early the headphones were crystal clear if you disconnect the case earth, the USB ports and the eSata port leaving only audio to the front. A bit of a sacrifice.
There was a silver lining to it all. Antec Australia said they had the part number wrong and are sending me the front assembly free of charge and complimentary.
I am a happy customer.