I am about 12 miles away from the transmitters according to antennaweb.org.
I have the Zenith Silver Sensor thing. Unamplified.
I get very weak signal on regular UHF analog, but all HD channels come in from 90-99%. I even pick up a Flagstaff station which is about a 1.5 hour drive up the hills. I am not sure how it gets any of that but it is pretty amazing.
What is your distance to the transmitters? You certainly do not need anything fancy, if you are within like 40 miles i think an amplified version will just cost you more. In chicago here we are about 26.8 miles from the transmitters and have a 16 year old UHF directional in the attic that picks everything off of the hancock building.
I am also blown away by the ability of these little chunks of metal to pick up such gorgeous reception!