I know absolutely nothing about digital reception.
From what I read though, a pre-amplifier can hurt the MyHD more than it can help.
An outdoor antenna wil *always* beat the pants off an indoor antenna. If you can have outdoor, I would not even consider indoor.
The rest of this post is for opinion purposes only and let's me blow off some steam.
I use two(!) antennas because I am in a place where the transmitters are about 120 degrees in different directions. I used to have a nice cheap non-directional antenna which worked pretty well for me. Then the FCC licensed a new FM station which located a tower on top of a high hill about 10 miles from me.
That FM station began giving me fits. It is supposed to be a low-powered (1,000 watts) non-commercial, but it is just like any other commercial station with a 1 song, 3 spot format. Because of that tower location that dinky 1k watter reaches over 40 miles. I could scarcely belive I could pick it up 40 miles away, but I did. A complaint filed by a commercial station competing with it fell on deaf ears at the FCC.
So I had to switch to two, amplified, highly directiona antennas. One is a 109" combo UHF/VHF pointing away from the offensive FM station. The other is an amplified large (30"?) UHF pointing at UHF stations.
I combine the signals right before it hits my tuner card and tweak the attentuation a bit so one signal does not cancel the other out. I must have tried everything, but this works the best.
I had to spend about ~$300 so that one more FM station could be added on a frequency that the FCC knew would cause me some trouble. Only after they licensed the new stations did they "discover" they had screwed up and it was worse than they had guessed, not just for me but for millions similarly affected. I had to poke around in their tech reports and learn all the lingo for days before I discovered the smoking gun "Oops" report.
As far as I am concerned, the FCC's major concern is slicing and dicing money. They represent "the people" about as well as GM does.