It seems like everybody is putting the words "High Definition" on their products. I'm not certain whether the FS1 High Definition Earphones from XtremeMac are a true high definition product, but it is a superior earphone.

From what I've read, the Xtreme Mac FS1 are made by "Future Sonics, makers of in-ear audio monitors that Professional Musicians use on stage". From what I heard, the sound is very fantastic. There is a lot of foam and padding in the earphones that really cuts off the rest of the world.

You should be able to purchase the Xtreme Mac FS1 High Definition Earphones for about $149.95 off their website.

Via Product Page